Timber Frame Construction | Types | Uses
Timber Frame Construction and “post-beam” construction are traditional methods of building heavy wood, using structures that are square and carefully fitted, and aligned with joints secured by large wooden pegs.
1. Ancient timber frame:
The definition of ‘traditional’ depends on the however way back in time one needs to travel. Early construction forms used the shape of trunks and limbs, which could be hewn with AN adz into a roughly rectangular cross-sectional – all as recently discovered on reality television!
For the needs of our rationalization, we’ll take into account timber frames designed on-site victimization solely sawn timbers for the frame. among our definition, their area unit 2 distinct sorts of timber frame:
Balloon
Platform.
Both area units were designed off masonry/concrete walls and foundations.
the alternative of ground floors is:
decorated timber
Solid concrete
For the decorated timber floor shown in Figure three.12:
each form begins with a ‘ring beam’ designed on a plate, each beam and plate to the masonry base with lag bolts.
The ring beam may well be either one timber or 2 timbers nailed along.
For the solid concrete floor, 2 potential foundation details area unit shown in Figure three.13:
A masonry wall and a separate floor block.
A poured concrete foundation, wall, and floor block bushed one. this is often} a standard style of construction in North America wherever the poured concrete wall can type a basement or semi-basement.
In either case, there’s no would like for a timber ring beam, and also the plate is lag fast to
the edge of the concrete floor block. On the timber ring beam construction, it had been traditional to fix a soleplate created from 2 timbers on their flat.
Platform construction suggests that having the studs one level high. On prime of those studs, the joists for a floor or platform area unit set; then another soleplate is ready down and studs for another level height are ready up.
In balloon construction, the stud height is ready for 2 stories. it’s not usually potential to urge timbers long enough for additional. The intermediate floor is joined to the center of the studs. Figures 3.14 and 3.15 illustrate each sort of construction.
In each instance, there’s an explicit quantity of fabrication however this can be done on-site and is usually done by taking one layer of the soleplate and fastening studs to that, all for one wall plane, capping the studs off with one runner.
All this can be done on the bottom of the floor block. Bracing of skinny wide timber is let into recesses cut within the soleplate, studs, and runners,
and dancing is superimposed within the height of the studs at regarding 750 centers. Finally, the frame is erected on the plate or spouse of the soleplate and also the 2 area unit nailed together; temporary bracing keeps the panel vertical.
A double runner is superimposed on the prime of the panels. With a platform frame, the double runner on the prime of the studs is employed as a control for the higher joists. Once this area unit is in position, another single soleplate is nailed to the highest of the joists, so that an additional level height set of panels is added; so on.
An additional runner is superimposed to the highest set of panels and it’s to the present double set of runners that the roof timbers area unit. during this type, and in balloon construction, it’s necessary that every one timber – joists, studs, and roof timbers – area unit at an equivalent center in order that loadings from the roof and higher pass on to studs, direct through-beam ends, etc.
In balloon frame construction the floor connection halfway up the stud length is supported partly by a skinny, wide timber referred to as a ribbon let into the inner face of the stud, and part by a halving joint of the beam to the stud and nailing to the stud.
The top of the framed panel is created with one runner and if a roof must be refastened at that level, the runner has doubled up an equivalent as within the platform frame.
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Typical sizes of timbers used are:
Studs, runners, sole and wall plates, dwangs or noggings – from 150×50 to two hundred × seventy-five
Bracing and ribands area unit usually thirty-two or thirty-eight thick and two hundred to 250 wide
Joists from 150× fifty to three hundred × seventy-five
Diagonal boarding twenty or twenty-five thick, a hundred and fifty or two hundred wide
Clap boarding and clapboard fifteen or twenty millimeters thick
Matchboarding is fifteen millimeters thick.
Once the frame is erected, the outer face is going to be lined with plain edged sawn boarding about 150–200 wide and 20–25 thick, set diagonally; the perimeters area unit butted tightly along and nailed double through the face to each timber – studs, sole plates, runners and dwangs.
This diagonal boarding has 2 purposes:
Being diagonally set, it contributes to the wrenching resistance of the frame
Nailing double to each underlying structural timber holds the frame tightly along
and contributes significantly to its strength. Once the diagonal boarding is fixed, a weathering surface is fixed in situ.
This can be of a spread of materials however is most of the soundproof layer sort, wherever rain is shed instead of absorbed and allowed to evaporate.
Materials normally used are:
Timber clapboard, shingles, clay tiles, and slate
A layer of hydrocarbon felt was placed over the diagonal boarding. terribly early examples used a ‘tarred paper’.
Modern materials utilized in renovation work embody plastics clapboard, concrete tiles, artificial slate and tile, fibre board sheathings, and profiled metal claddings.
Whatever is employed it’s necessary to permit the previous frame to breathe. It should not be sealed by any means. The inner face is accustomed either to timber match boarding and/or timber slat and plaster.
The void between the 2 layers was ofttimes left empty, which suggests a chilly house. If the climate was terribly cold, vegetable fibre like straw, grass, reed, heather, moss, etc. would be packed in to enhance the insulation. If the weathering face poor down and leaked water into the development, speedy decay befell as none of the timber was
treated with preservative.
No vapor management layer was placed behind the inner – they hadn’t been fancied. With no vapor management layer, wet from the within was ready to tolerate the wall till it reached the tarred paper or hydrocarbon felt.
Here is condensed and also the currently ‘solid’ water wetted the boarding, inflicting speedy decomposition of board and timbers. while not either tarred paper or vapor management layer, the wall may ‘breathe’, and any condensation on the rear of the outer boarding may evaporate away, even if solely slowly.
Once the mechanisms of moisture passing through the wall to condense behind a cold
the impervious layer is understood, it is easy to work out a solution:
provide a gap between the tarred paper or bituminous felt and the diagonal boarding, and allow this gap to be ventilated, as shown in Figure 3.16.
This can be done by simply applying vertical battens to the face of the diagonal boarding to which the paper or felt is fixed, followed by the weathering skin. Allow this space to remain open top and bottom and it ventilates naturally.
2. Modern timber frame construction
Modern timber frame is constructed on the platform frame model and employs several of the same concepts because the ancient forms however apply plant fabrication, regular stress graded timbers, and plyboard or bound strand board protection panels rather than diagonal boarding, thus there’s no want for bracings, the protection shares the loading supported by the wall panels, timbers square measure abundant smaller in crosswise and the protective covering is usually a masonry skin 75–102.5 thick of brick or block, facing brick or with a roughcast finish.
Weather boarding is additionally used, either of natural timber or of plastics, and this is able to vertical treated timber straps nailed over the studs within the panels. The skin of sheet boarding is such an associate integral part of the ready-made panels that the development type ought to extremely be termed a stressed skin panel.
Once the panels square measure delivered to the location, they’re erected on a sole plate or plate. They arrive coated with a layer of building paper. The building paper is pinned on through the serious plastic tape that prevents the paper from tearing at the staples.
The tape is comparable to it utilized by suppliers and merchants to bind bundles of their material. Building paper is a hydrocarbon sure paper or, a lot of ordinarily currently, an artificial fibre (usual polypropylene) unwoven membrane-like Corovin or Tyvek.
Once the panels square measure erected and braced up-right, the roof is placed on. once weathertight –at least a minimum of felt in situ and counter battened – the panel frame is filled with a glass or insulator insulation, a vapor management layer is also applied, sometimes wallboard however additionally alternative sheet materials furthermore as timber paneling. Figure 3.17 shows a timber frame construction at substructure level, Figure 3.18 shows
that construction at overhang level, and Figure three.19 shows the junction of associate higher with the timber panels. Note that heaps of the annotation have been omitted for the sake of clarity. On properly scaled detail drawings the annotation would be complete, either on the detail or during a notes column.
It is vital to note:
The limitation straps constitutional each 2000 millimeter about and nailed to the studding – Figure 3.20. Note the building paper was turned all the way down to cowl the joists and ring beam.
The weeps constitutional each fourth or fifth brick, high and bottom of the outer leaf of
masonry to ventilate the cavity and keep the surface of the timber frame panels dry –
Figure 3.21.
Note however this cry comes beyond the face of the blockwork to accommodate the render to be applied. On the surface, a layer of masonry is constructed of the muse to administer a fifty-millimeter cavity next to the timber frame panel.
Wall ties square measure nailed to the studs of the panel and designed into the courses of the masonry – 3 to four per centare with further ties at quoins, intersections, and openings. Nailing ought to extremely be with 2 nails per tie, associated an improved nail would be best. sadly, few
bricklayers square measures ready to travel to the length of fixing quite one nail, and therefore the use of improved nails is often a matter of what {they square measure|they’re} given! Specialties are offered that have holes for nails at one finish and a ‘grip’ for bedding into a mortar joint.
Figure 3.22 shows 2 samples of those ties. The masonry is of:
[*fr1] brick thick masonry, either facing brick or commons, with a roughcast
Blockwork seventy-five or a hundred thick and roughcast
a hundred thick fair-faced blockwork, natural, artificial or reconstructed stone. though the weeps are antecedently delineated as ‘ventilating’ the cavity fashioned, the lowest weeps additionally act as cavity drains.
The ventilation of underfloor voids should be sealed off from the cavity by use of a liner to stop the unfold of fire from the underfloor void to the cavity and contrariwise.
A fire stop of timber a minimum of fifty thick (measured within the direction of the cavity) should be nailed to the highest of the panels to stop the unfold of fire either to or from the intermediate floor or the roof void.
Each ‘separation’ of the cavity should be aired with weeps high and bottom. the main points {you do|you square measure doing}n’t see are usually a lot of vital than those you do. The wall panels we’ve got checked out earlier were all fire stopped horizontally to cut back the unfold of fire up the cavity between the panel and protective covering.
However, there’s a necessity to stop vertically to cut back the unfold of fire horizontally. this is often done at corners; Figure three.23 provides a detail whereas Figure three.24 shows a photograph. what’s not straightaway apparent within the photograph is that the horizontal fire stop is there, however, shows solely as a bump below the breather paper – just under the scaffold boards.
Now, why didn’t the builder place up the corner ones furthermore, then place them on the building paper? Well, the panels keep company with the paper already fixed in situ and then once the paper from the higher panels was born, it coated the fire stop. Then they came on and fixed the corner fire stops.
But they got it all wrong. The breather paper, whereas foul solid water, will thus solely
when the surface of the membrane is open, free, and unobscured. If it’s ironed between
a fire stop and therefore the masonry, it’ll attract water sort of a sponge once a brief amount.
What created things worse on this specific website was that the builder failed to place any DPC on high of the fire stops, that was untreated timber – a formula for rot and ensuant disaster. however, there was one mistake that was ne’er photographed.
The metal straps connection higher and lower panels across the higher ring- beam ought to bear before the breather papers are fixed down so the workmen will see wherever the studs are.
On this website, they were fixed later so a number of the straps were nailed solely to the frame protection, the OSB (oriented strand board), that was solely eleven thick, and that they were bent to return over the horizontal fire stop.
They were so not straight and tight across the junction. This additionally meant that they were pressing against the within the face of the masonry skin.
The rules, therefore, are:
(1) work straps across higher junctions before fixing the membranes down or fire stopping is fitted.
(2) Fix straps down into substructure before fixing the membranes down.
(3) Breather membranes ought to be completed over the completion of the timber frame panels before the other work is administrated.
(4) fireplace stopping of treated timber ought to be fixed over the membrane.
(5) DPC material ought to be fixed over the fire stopping.
(6) No breather membrane between the fire stop and also the masonry protective cover.
Figure 3.25 could be a photograph of a ground floor designed on a block substructure and prepared to have wall panels erected thereon. The plate with the ring beam and also the soleplate electronic device are all there around the outside.
Then there are sleeper joists with solid strutting across the mid-span of the joists. what’s not very clear is that the 2 sleeper walls with wall plates support the joists at their mid-third points.
Figure 3.26 shows panels erected on such a base four. However, one will establish all the timbers. Notice however the vent liner has not been properly inbuilt.
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