Door Linings
Within most commercial and residential buildings in the Western world, the passages between rooms are generally secured through the use of hung doors. These doors provide privacy, heat retention, sound insulation, as well as decorative qualities, and are a standard component within our homes. With that in mind, for doors to keep up with the frequent use that they experience, a solid fixing point is required. For modern internal doors, these components are known as door linings.
What is a door lining?
A door lining is a timber component that is used to house internal doors and is securely fixed within a larger opening within a partition. When fitted correctly, the door lining provides a solid surface onto which the hinges and other ironmongery of the door can be chopped into and fastened to. The outer edges of the fitted lining also provide a point of registration for the wall surface covering to come into. Additionally, the door stops and architrave - components necessary for the successful installation of the door during the second fix process - are fastened to the door lining. Modern door linings are available for purchase from most merchants in the form of kits, featuring 2 standard length jambs and a pre-housed head that are assembled to form 1 door lining.
The ideal width between the two jambs of a door lining is the width of the desired door plus 3/16”-¼”, or 5-6mm. This will allow for a consistent ⅛”/3mm gap down both sides of the door once it is hung, with the gap on one side being defined by the offset of the hinges. For standard quality hinges, this gap on the hinge side of the door between the door and the lining is ⅛”/3mm, and so when hanging the door, a consistent margin should be achieved down both sides and across the top of the door. The perfect width of these linings is important when marking out and housing custom width linings. In residential renovations, not every opening is capable of receiving a standard width door, and as such, a custom lining must be made from lining material. There is a fair amount of nuance when fitting door linings, though overall they are not a difficult component to get right. The critical part is walking away from the finished lining knowing it is installed perfectly. If the lining is installed correctly, then hanging the door at a later date will be straightforward.
What are the criteria for the installation of joists?
The correct installation of a door lining is imperative to the easy installation of the door at a later date. Attention to the width of the lining material needs to be paid when selecting and creating the lining. Prior allowances should have already been made within the masonry or stud partition to receive the lining. For 1” thick lining material, the rough opening should be 2 ½” larger than the width of the door, to allow for the two thicknesses of jamb, and ½” for packing/shimming. The correct width between the two jambs of the lining needs to be selected in relation to the width of the door. This width is 3/16-¼” larger than the width of the desired door. The width of the lining material itself needs to be selected in accordance with the thickness of the opening material. This width needs to accommodate the covering of the finished wall surface, such as tiles or plaster, with the correct width of lining material being flush with both finished outer wall surfaces.
For standard linings fitted within 4”x2” CLS stud partition openings, this width is 120mm, with the lining being installed 2mm past each side of the plasterboard to allow for 2 coats of skim to come into it. The height of the lining also needs to accommodate the desired height of the door within it, with an ⅛” gap between the top of the door and the bottom of the head of the lining, and an appropriate gap between the bottom of the door and the floor. For standard height doors (6’6”/78”/1981mm), the height of the overall lining is somewhere between 2010mm/79⅛” and 2020mm/79½”, depending on the manufacturer of the lining. When these linings are fitted in their full height onto the finished floor (subfloor without floor covering such as carpet or tiles), the space from the floor to the underside of the head of the lining will allow for a full-sized door to be swung. The height from the finished floor to the underside of the rough opening should therefore be 80”, to allow for the lining to slide in smoothly, and be shimmed if required. An additional inch should be allowed for height when setting out the rough opening from the top of timber joists before the finished subfloor is installed.
The distance between the bottom of the door and the finished subfloor needs to be between 10mm and 22mm, depending on the thickness of the floor covering. The jambs of the lining should be installed perfectly plumb, with a slight outwards belly to ensure that the door does not bind during the hanging stage (this belly can be pulled back in again with wedges once the door is swung to achieve an even margin). The head of the lining should also be level, and overall, both of the jambs should be square to the head. The bottom of the jambs should be spaced apart from each other the same distance as the fixed distance between the tops of the jambs. Additionally, the bottom of the jambs should be parallel to each other across their width, eliminating any twist in the lining.
How are door linings installed?
Installing a door lining to a suitable standard is straightforward, provided all of the steps are followed. The first step to installing a door lining is deciding upon the correct size of the component. A suitable height and width for the rough opening should have already been established in accordance with the criteria above to accommodate the desired sized door, and so a measurement of the rough opening can be taken to determine the correct width lining. For reference, the actual overall width of the lining is 2¼” wider than the width of the door that will fit inside it - 2 x 1” jambs + ¼” for the margin down each side of the door. In modern construction, the opening that will receive the lining will be around 2½” wider than the door, to allow around ¼” between the lining and opening for packing/shimming purposes. In traditional practices, the openings were often made tight to the width of the lining, though more issues can arise here with the lack of space for shimming. With this in mind the correct sized lining needs to be purchased or made. Most custom sizes of linings can be acquired from specialist suppliers, with common merchants typically stocking only the common sizes of linings, namely those for 27”, 30”, and 33” doors. Often, these lining kits will feature a different set of housing on either side of the head for different sized doors. In addition to the correct width of lining for the door being chosen, the correct width for the thickness of the opening needs to be decided upon. As mentioned, this width needs to be chosen in relation to the thickness of the finished partition. The illustrations show some of the common width of lining and the partitions that they fit into.
The width of the lining material is determined by the thickness of the partition that houses it. In all scenarios, the lining should sit flush or slightly proud of the finished wall surface covering, and so the exact width can be calculated backwards from this. A standard 4” CLS stud with 12.5mm plasterboard on either side produces a wall thickness of 120mm, and so a 120-122mm (merchant depending) width lining is applicable. If one or both of these faces are to be tiled, then an additional allowance needs to be added for each face of tile. For common 100mm internal masonry partitions, plastered in a traditional fashion, the thickness of the wall will come out at around 130mm, depending on the exact thickness of the hardwall/plaster. For masonry walls (100mm) that are dry lined, the total thickness of the partition becomes 140-160mm (20-30mm allowance for each dry lined face). Smaller and larger standard sizes can be purchased and ripped down to accommodate any number of variations in thickness. For new builds, the sizes are going to follow a relatively standard pattern. In renovation scenarios where existing walls may have already been plastered multiple times, the lining should be cut down to accommodate the existing thickness.
Extra wide openings may sometimes require the use of 25mm/1” plywood to be ripped down for the creation of the lining material. In residential renovations, extension work can often lead to doors being fitted into cavity masonry openings. If a lining is to be fitted in the traditional style in these wide openings, with the lining spanning the whole openings with architrave being fitted on both sides, then the lining must be cut from plywood. This being said, sometimes, depending on the scenario, cutting the lining to this extreme width can cause issues in terms of the finish or in terms of timber movement. As such, using a regular width lining and returning the wall finish round the corner and into the side of the lining is the best choice.
To house out a custom sized head, the procedure is as follows. Once the correct width of material is determined, the housing can be marked out. A 1” horn is marked in from the end of the material to allow for ease of assembly. This horn will be cut off after the lining is assembled but forms a dado in which the jamb can be easily registered into. Whilst the head of the lining can be accurately laid out first and then cut all in one go, the most accuracy comes from cutting the first housing, and then registering off of the dado shoulder to mark the other housing. As such, the first housing is cut before setting out the second. From the 1” inset mark, another mark is made 1” in from this. This is the approximate layout for the first housing. Using a square, follow these lines over both edges of the material. Take a marking gauge and set the depth to half the thickness of the head material, or ½”. Using the gauge, the two depth lines are connected on both edges of the head. This line is the definitive depth of our housing, at half the thickness of the material. The maximum accuracy for cutting the housing is achieved by using the thickness of the material itself to layout the housing, and so we will start by cutting the outside of the housing to depth in order to create a registration point for the other cut.
Using either a handsaw or a chop saw set to depth, cut the outside line of the housing down to depth, making sure to keep the saw straight in the cut, on the inside of the line, and not past the depth line of the housing. With this line cut to depth, an offcut of the lining material can be placed on top of the housing. Line the offcut up with the outside wall that was just cut and use a marking knife to mark the other outside wall. Any inaccuracies in our rough layout will show here, with the knife cut possibly falling out of line with our original 1” mark. Use a sharp chisel to create a small notch in the timber on the inside of the housing. This groove will give us a positive registration point for the saw to start in. This step is not necessary when using a chop saw. If the notch is not deep enough, register the knife back in the groove on the inside of the wall, and slide a square up to it. Make another pass with the knife and use a chisel to make the notch deeper. Once a positive groove has been established, use a saw to cut this housing wall down to the depth line again.
With the housing width established, use a saw to make several cuts through the waste material, ensuring to stay slightly above the depth line. With several cuts made in the waste, take a sharp chisel of the correct size and begin to remove the waste from one side. Make sure not to pass all the way through the housing with the chisel, as the soft pine lining material will tend to chip out on the unsupported edge. To avoid this, come in from each side up to the halfway point, removing the waste material down to the depth line. The inside of the housing should be flat from edge to edge once the outer depth lines are reached, or alternatively slightly dished to ensure that the jamb will fully seat to the outside of the header, keeping the joint tight. Alternatively, the housing can be cut with a router, though this a modern adaptation, and not necessarily any faster when considering the set up time of the router.
From here, hook a tape measure on the inside of the first housing, and make an accurate mark at the desired width for the door. Remember, this width will be the thickness of the door plus 3/16”/1/4” of an inch. With this mark made, use a square to register this definite mark. Use the same method as before to cut this housing accurately to depth. From the outside of the second housing, mark another 1” inset mark for the horn, and cut the head away from the length of stock at this point. We now have a fully housed header ready for assembly.
From here, we need to cut the jambs to length from the length of custom stock. The length of the jamb can be worked out by marking the different spacings on the material, or by simply measuring the length of a pre-cut kit jamb. These pre-cut jambs are around 79” to accommodate a full height door, though a custom lining may be shorter than this. To calculate the length of the jamb, take the length of jamb material to the bench. Mark the depth of the housing, or ½” in from the end. From this line, a ⅛” gap is required from the bottom of the head to the top of the door. From this line, make another mark down the length of material the height of the door that will be swung in it. Then finally, from this mark, make another mark at around ½” from the bottom of the door. This mark is where the jamb will be cut off, allowing for a ½”/12mm gap between the unfinished floor and the bottom of the door. The underside of the door can always be cut off if the floor covering comes up too close to the bottom of the door.
With the jambs cut to length, the procedure for assembling the lining can begin, which is the same for both pre-cut kits and custom sized linings. A clear, open area is preferable for the easy assembly of door linings. Sight down the length of both of the jambs, checking for the direction of the inevitable bow in each. Arrange these jambs so that the direction of the bow is facing outwards away from the centre of the lining. For ease of assembly, lay these jambs on the floor in the correct orientation with the bottom of them touching a wall. Space them apart correctly and place the head on the floor near the top of the jambs. Slide all the timbers around so that the top of both of the jambs are just touching the surface of the head before the housing starts. Using a hammer, tap the housings over the jambs. A sharp chisel can be used to pare down the outside shoulder of the housing if they are too tight to fit the ends of their jambs. Once the jambs are fully seated in the housings, use a block and hammer to tap the front face of all the components flush with one another. Bear in mind that this joint will be on show, so take care not to damage anything here. With the jambs seated correctly, take a countersink pre-drill and drill two to three holes through the top side of the header, through the housings and into the tops of the jambs. Using a driver, install 70-80mm screws into all the holes. This will securely hold the jambs in place in the housings. PVA wood glue can be applied to the end of the jambs and in the housing for extra hold if desired.
At this point, the lining is ready for installation, though there are a few extra steps we can take first to make the process easier. Using a piece of ply, an offcut of lining material, or a length of timber the same width as the lining material, cut a spacer block that is the exact width of the distance between the two jambs at the top of the lining. This block will help us to keep the bottoms of the jambs the perfect distance away from each other during the installation. Without any bracing the lining is a little fragile to move, with the potential of the housings breaking or coming loose if unsupported. As such, we can install some braces on the lining to help combat this issue. At the bottom of the lining, approximately 6 or so inches up from the very bottom, insert the spacer we just cut between the two jambs. Take a length of batten and line one edge up with the outside edge of one of the jambs. Use a second fix nailer to pin this batten in place. On the jamb, ensure the spacer is tightly pinched between the two, and pin the batten in place again. Cut off the excess batten if required and flip the lining over. Install another batten in the same fashion, ensuring the jambs are in full contact with the edge of the spacer. With this achieved, the spacer can be removed. The jambs are now secured the correct distance apart from each other, with the battens high enough off of the floor to allow us to easily install the bottom fixing of the jambs during installation. At the top of the lining, take another batten and place it at approximately 45 degrees on the material, with the batten contacting the head at around ¼ of the width in from the end of the head, and the other end on the hinge side of the lining. Pin this end in place, and use either a square or the 3,4,5 trick to square the head to the hinge side of the lining. Pin the other end of the batten in place and cut off the excess. This will roughly hold the lining square during the installation process. Using a saw, cut off the horns on either side of the lining, and stand the lining upright. These steps are not critical but are beneficial for the preservation of the linings if they are being made in advance.
Using a countersunk predrill, make a series of evenly spaced holes down the length of each jamb, 2 holes wide by ⅘ holes deep. Ensure none of the holes fall 6 inches down from the head or 9 inches up from the bottom of the lining, as the screws installed in them will clash with the location of the hinges of the doors. The centre point between these two markings should also be avoided, as the centre hinge of a door with 3 hinges will conflict with this location. At this stage, the lining can be lifted into place within the rough opening.
With the lining stood up in the rough opening, take a preliminary measure of the head by using a small level. Doing so will give us an indication if either side of the lining needs to be lifted up due to an uneven floor. Placing a 3mm spacer underneath the hinge side of the lining is good practice regardless, as it gives us some leeway when levelling the head. The first step now is to get a single fixing in the top of the hinge side of the lining. The lining needs to be centred in the opening before fixing, and a 3mm packer should be placed behind the hole and the surface of the opening. For regular un-boarded studwork, a 15mm spacer can be used to align the front edge of the high side of the lining up off of the timber stud. If the stud is already boarded, a 2/3mm packer can be used for the same purpose to simulate the thickness of the plaster. For any other types of walls covering, the correct allowances need to be made to keep the lining in the correct alignment.
With the front edge of the top of the hinge side of the lining in place, and with a 3mm packer behind the hole, insert a 70mm half threaded screw into the hole. These partially threaded screws will thread into the surface behind but can be slightly loosened without needing to be removed in order to pack the lining. For linings that are being fixed to masonry with plugs and screws, a larger pre-drill should be used on the lining in order to minimise the amount that the SDS will shake the lining during the installation of the first fixing. With the first fixing in place and the top corner of the lining in the correct location, the hardest part is completed. Using a spirit level, plumb the outside edge of the lining. Doing so should leave an even margin between the front edge of the lining and the face of the wall. If not, every effort should be made to keep the lining plumb, with absolutely minimal adjustments being made to try and bring it into line with the out of plumb opening surface. With the outside face of the hinge side plumbed up, install another fixing at the bottom of the lining with another 3mm packer behind it. From here we can check to see if the inside face of the lining is plumb. If for some reason the middle of the jamb is bellied inwards, install a screw without a packer behind it and pull it into the opening surface. For now, we need to check if the jamb is plumb from top to bottom. Add or remove packers until the jamb is plumb from top to bottom, by loosening the half-threaded screws slightly. In the other holes top and bottom, add the same sized packers and fix the lining securely. Using the level as a straight edge, pack the middle of the lining until the face of the jamb kisses the level. A slight outwards belly of around 1-2 can be left at this point, to be pulled back in again during the installation of the door. Hold the top of the level tight into the top of the hinge side jamb to check that an unintentional belly hasn't been left anywhere in the jamb.
With the hinge side fully fixed, we can level the head and fix the other jamb. As a general rule, no fixings are inserted through the head of the linings, only through the two jambs. Using a small level, level the head, adjusting it up and down through the use of packers under the bottom of the unfixed jamb. Once the head is level, use the same spacer as before to bring the front edge of the lining out to the appropriate alignment with the finished surface of the wall. Using packers, fill the remaining gap left between the back of the unfixed jamb and the surface of the opening, and install a screw at the top of the jamb. Repeat the process of fixing this jamb again, fixing the top and bottom and then the middle to a level. At this point use the timber spacer from earlier to ensure that there is no twist in the lining, making sure the square edges of the spacer make full contact with the faces of the jambs. Once all of the screws are installed, the lining is essentially completed, and the timber spacers and battens can all be removed. The lining can be kited by eye or through the use of a crossed string line to ensure that there is no twist present. Typically, if the previous steps are followed correctly, a single door lining very rarely possesses any twist. The only scenario where this is more likely to occur is if the lining is being fitted to meet the face of an already plastered wall. In this instance, with the faces of the lining aligned with the finished surface of the walls, the lining might possess a twist. To rectify this issue, the non-hinge jamb should be unscrewed bar the top screws and pulled around until the twist is removed. Kiting a door lining is far more important for the installation of double doors.
Fixing a door lining directly into masonry can often be a hassle, particularly for beginners, as the extra steps of drilling and installing the wall plugs make the process very awkward, especially whilst trying to keep the lining in the desired orientation. As such, there are a few steps that can be taken to ease the installation. The opening in the masonry can be made larger than necessary in order to allow for timber grounding to be installed to the sides of the opening. By planting timbers on these surfaces, the lining can be directly screwed into this timber in the method that we previously looked at. Another very traditional method that is not utilised as often in modern construction features the use of timber propeller wedges. These wedges were cut on site by carpenters and installed within the muck joints of the masonry openings to allow for a solid timber pickup. The wedges are cut with a small hatchet, from a length of lining material. Offcuts of lining material are chopped away on each side at an angle, scalloping the material and revealing a twisted propeller shaped timber once completed. As the wedge scoops and curves, the opposing end becomes thinner. At roughly around 5-6 evenly spaced mortar joints in the masonry opening, the dry mortar is raked out and the wedges are installed. As the wedge is driven in, it spins in the opening and is securely wedged placed. With all the wedges installed, they are cut off perfectly plumb to either a plumb bob or a spirit level. These wedges are installed on both sides of the masonry opening, and the distance between the two plumb cuts is calculated to the perfect width of the lining. Adjustments for packing can be made by installing a packer between the back of the lining and the face of the wedge, or by running a saw between the two to increase the gap. From this point, screws can be used to screw through the lining and into these wedges, though traditionally cut nails would have been used. Surprisingly, though this method is more traditional and not used as often in modern construction, linings fitted in this fashion are some of the most secure in existence, as anyone who has attempted to rip them out will know.
Another small aside about traditional linings was the type of housings that were cut in the heads. Whilst modern production methods opt for straight through housing due to ease of manufacturing, traditional hand cut housings in lining heads were tongued housings, with the ends of the jambs being rebated for additional stability of the joint. These types of joints can still be found in older properties when carrying out demolition works.
Whilst the above procedures apply to the installation of standard single door linings, there are a few other types of linings with different pertinent features. The general process for the creation and installation of all of these linings are fairly similar, though there are some differences. Here is a collection of the pertinent differences of each type.
Extended linings with skylights/fanlights/transom lights
Whilst not such a common component in modern construction, feature fanlights above internal doors were very fashionable during the early to mid-1900’s. These decorative yet functional components consist of an extended door lining that features a built-in frame above the door. These tall linings, sometimes known as storey frames (as they span from the floor to the ceiling within a room - the whole storey), frequently house some form of glass within the top portion of the lining. These windows allow light to pass between rooms without removing any of the privacy offered by doors. This offers improvements to a room's natural lighting in scenarios where other forms of light are limited, or traditionally in a time when windows were smaller and electric light bulbs were dimmer. It's not uncommon to still find these traditional skylights in older residential properties that have not been remodelled, as well as seeing the original lining having been filled in with MDF or hardboard, as the style fell out of fashion.
Most typically the frames above the door featured a fixed pane of glass, held in place with decorative beading and window putty. Other styles of fanlights featured custom made fixed or moving window sashes, as well as slatted glass features for ventilation purposes. Seeing as the glass assembly is contained within a portion of the actual lining, a few extra steps need to be carried out when setting out and assembling these custom frames. Primarily, the total height of the lining increases from that of a standard height to also include the height of the fanlight. For storey frames, these linings extend from floor to ceiling, ordinarily with enough room between the head of the lining and the ceiling to install a full set of architraves around the lining. These storey frames are suitable for installation in rooms with or without coving, as any coving comes to a stop end or return around these frames. Alternatively, the extended lining may fall short of the ceiling to allow for a small bulkhead above the window between the top of the architrave and the ceiling. This scenario is also suitable for running coving above the fanlight.
To make this custom lining, take a measurement of the total height of the opening. For non-storey frames, a measurement of the opening with a small tolerance for ease of fitting should be taken. For storey frames, a consideration should be made to reduce the height of the lining slightly to allow for the architrave to be installed correctly. With the height of the lining marked on a length of lining material, start from the bottom of the length and work out the height for the door housing (½” from bottom of lining to bottom of the door, then the height of the door, then the ⅛” margin on top of the door). This mark is the underside of the door header, also known as a transom in this scenario (hence the term transom light/window), with a transom being a horizontal rail that separates a door/window from another window. Due to the construction of this frame, this header/transom is housed into the sides of the jambs. Take note that traditionally these would have been tongued, through housings. Mark out the housing for the transom in the method we used previously, then mark out the head of the lining. From the very top of the jamb, layout the housing for the top rail, and cut both of the housing for the header and the transom. With both the housings cut and the transom and top header installed, we have a regular lining ready to receive a door, with an additional built-in frame on top, with the size of the window being whatever remains.
For fitting single panes of glass, the procedure is very simple and is easiest when the lining is installed. The glass pane is typically centred in the width of the lining. Mark the centre point and expand it outwards half the thickness of the pane of glass, plus a few mm. Use a square to mark this point all the way around the frame and using small window bead pins and the desired bead, fix a set to this line. Apply window putty to the back edge of this fixed bead and place the glass up against it. Use more putty to secure the glass from the other side into the frame and then install the bead on the other side. For other types of glass assemblies in the frame at the top of the lining, such as sashes, fit them in accordance with typical window fitting procedures.
Double door linings
These linings are very similar to regular linings in their construction, save for the extra width. When assembling these linings, space between the housings on the header must be the width of both doors (both the same size or a master and slave) plus ⅜” gap, for the margin down either side of the door plus an additional ⅛” gap between the two doors. When installing this lining, the master door side of the lining should be hung first, out of good practice. During the installation process, it's imperative that the head is correctly levelled, as any discrepancies in the head of the lining will show in the heads of the door not lining up with each other. Secondarily, the lining must be kited or checked thoroughly with a string line to check for winding in the lining. If the lining possesses a twist, then the inside faces of the two doors will appear twisted to each other when closed. To check the lining for twist with a line, tack a nail into each corner of the lining after installation. Attach a string line to one of the top nails and loop it around the nail in the diagonally opposite corner. Pull the string up from this nail, loop it around the top nail, and then again diagonally from this one. The line now creates a cross and provided the string on each nail is also touching the lining, this cross displays any twist in the lining. If the lines don't meet in the middle, or if they are pushing against each other, the lining has some twist in it, and one or both of the jambs are leaning out of the plumb. To correct this, move the jamb/s laterally along the plane of plumb, until the two lines just kiss in the middle. This ensures that both of the jambs are in the same vertical plane with each other and should also be plumb. This method can also be used to check regular lining for twist, though it is less imperative on single doors.
Angled linings
During the construction process, areas of floor space are often sectioned off due to restricted head height, such as under stairs or in loft conversion voids. Whilst these areas are not habitable spaces, they are perfect for storage and are typically utilised as such. Within loft conversion scenarios as well as under stairs, the walls that would receive a small cupboard door are sloped/angled, and as such require a sloped or angled door in order to maximise the size of the door. In order to effectively fit a sloped door, a sloped lining needs to be in place to receive it. These linings are very similar in construction to regular linings, with only a few variations. These linings are often much shorter and less wide than standard door linings also. The easiest way to assemble these lining is as follows.
Use a bevel to find the angle of the slope and transfer this angle to the top of the two jambs. Cut these angles on the jambs. For a short lining, a single length of lining material can be cut in half with the angle, resulting in two lengths with the correct top cut. Accurately laying out the head of the lining is the most intricate part of this process but is not difficult if accuracy is maintained. Take a full length of lining material and mark in the typical inch for the horn of the lining. Mark a centre depth mark on the edge of the header and use the bevel again to roughly layout the side wall for the angled housing. Use the thickness of the lining material to layout and cut the first housing. On a flat surface, dry fit the jamb into the housing and use the bevel to align it to the correct angle. Cut a timber spacer the same width as the door plus 3/16” for the margin. Use a square and the spacer butted up to the inside of the dry fitted jamb to find the point where the top side of the other end of the spacer contacts the underside of the header. Mark this point, as this is the inside face of the other layout of this housing and cut and fit the jamb. At this point, the length of material with the header on can be cut off with an inch overhang for the horn. From here, assemble and fit the lining in accordance with the standard procedure for a regular lining. The legs will need to be cut off after the fact to the height of the opening.
Additional tips
Where multiple linings are installed within close proximity to one another, such as in a hallway, all of the heads of the linings should be level with one another, to maintain a professional aesthetic. A laser level or datum line can be struck around the area at the height of the underside of the linings to maintain precision. Where multiple doors are installed within one plane of a partition, a string line should be pulled between the far jambs at both the top and bottom of the linings to ensure that all components are perfectly in line with one another. Failure to check this can result in the linings appearing “off” aesthetically with one another.
Door frames
Door frames are another variation of a door housing and are primarily used in external applications. The frame itself features a pre-assembled head, jambs, and bottom sill that encompass the installed door. The frame features a machined rebate that provides suitable weather resistant properties for use in external applications. Frames of this type are also required for installation between houses and adjoined garages for fire safety purposes, with most styles of frames being manufactured in compliance with fire safety regulations. Depending on the manufacturers, the inside of the frames may also feature gaskets, weather bars, and intumescent strips. For all intents and purposes, these frames are installed in the same fashion as typical linings. When installed in exterior applications, they are seated to the back of the external masonry.