Loft conversion in a timber framed house

[bernardgreen]

Do pay attention bernardgreen, that was established at post No. 3.

It's traditional timber frame/panels. To be more specific, 90*40 c16 timbers sheeted with osb.

There is a wide range of constructions from rigid braced frames ( tradditional ) with non structural in-fill to structural panels with minimal framing intended to keep the panels in place. Some constructions rely on the panels for the majority if not all the bracing of the frames.

Then there are slab built houses, just panels with no framing.

The load bearing may be all on the frame, all on the panels or shared between them.

if traditional timber frame then it will have been built by chippies off some site specific drawings, not from a 'timber frame company'

The word "kit" suggests it may have been delivered as a set of pre-cut timbers which could be assembled on site by company staff, local chippies or the home owner as a DIY project.

 

[freddiemercurystwin]

There is a wide range of constructions from rigid braced frames ( tradditional ) with non structural in-fill to structural panels with minimal framing intended to keep the panels in place. Some constructions rely on the panels for the majority if not all the bracing of the frames.

Then there are slab built houses, just panels with no framing.

The load bearing may be all on the frame, all on the panels or shared between them.



The word "kit" suggests it may have been delivered as a set of pre-cut timbers which could be assembled on site by company staff, local chippies or the home owner as a DIY project.

DO you actually have anything useful to add or are you just here to muddy the water?

 

[Jon6838]

Sorry for the confusion, when i say timber kit I mean the method used by most housebuilders these days. All the site managers I deal with refer to them as timber kit although this phrase may cover other systems I suppose.
To clarify, opening up the wall from the inside would be in this order: plasterboard, timber studs with glass wool in between and osb on the back, cavity, external skin of block/brick

 

[freddiemercurystwin]

Yes just standard timber frame, not a kit.

As mentioned you'll either need the original drawings/specifications and/or some opening up of the existing may be in order.

 

[Jon6838]

Thanks freddymercurystwin, I was just trying to get an idea of how it would have to be done before getting an engineer involved. I wouldn't like to get one out only to find it wouldn't be worthwhile doing. I just thought someone may have done or had experience in doing this style of house. I don't mind opening up walls to put studs in but this would be a major issue at one side of the house with the kitchen and stairs in front of the wall. I suppose it's a catch 22, I don't mind spending money on an engineer, but I don't like wasting it!
There have been two other houses in my development (dundas homes) that have had their loft converted, one with a dormer. I got the number for the builder that done them but can't get a hold of them.

 

[freddiemercurystwin]

Have you asked those owners for a look-see at their drawings they had done for the works? Or spoken with the owners to see how invasive the work was etc?

 

[Jon6838]

I have asked one of the owners if there was any disruption to the downstairs walls and she said she wasn't 100% sure but she didn't think so. I never asked to see the drawings though, that's a good shout

 

[bernardgreen]

DO you actually have anything useful to add or are you just here to muddy the water?

I was making the point that there are several ways to build a house with timber as the load bearing material. It is cost cutting in the mass housing construction industry that has "muddied the water".

SIPs were designed with two skins of plywood or OSB. Changing the design to have one skin of plaster board has reduced over all build cost but adds a failure node to the "SIP" SIPs with two plywood skins resist bowing in any direction, "SIP"s with a plasterboard skin have much reduced resistance to bowing as the plaster board when under tension will crack.

 

[tony1851]

I wouldn't even contemplate resting a steel on them as is, I am just trying to get an idea of the different methods (if any) of converting this kind of roof as timber kits are the most common build these days and every loft conversion company seems to convert them no problem, yet all the videos and pics available all have block walls for the beams. I don't mind opening up walls to put in more studs if that's the only way to do it but that's eight areas of the house to open the walls, 2 of which has a staircase and kitchen in front of them!!
Even if this was the way forward and I added all the extra studs, the beam would still only be resting on the 90mm wide timber in the loft, I thought the minimum was 100mm?

There is no problem in supporting steel beams off studwork, as long as there is a decent-size timber plate on top. But as it would be a concentrated load, the stud(s) would need to be checked by an SE.

 

[Jon6838]

Hi again, after endless searching I have managed to find a pic that shows my exact situation, with steels resting on the timber frame. Although the way it’s been done in the pic doesn’t look sufficient to me! If u zoom in it looks as though a piece of timber has been fixed to the stud work with the steel resting on that. Same with the ridge beam. Is this an acceptable method? If it is I’m a happy bunny

 

[tony1851]

The steel ridge beam won't be supported off the horizontal piece of timber, otherwise a considerable portion of the roof would be carried only by a few nails or screws; it will be going onto a timber plate directly above the studs (note the doubled-up studs-there is probably another pair just off the pic).
Can't see what's happening with the steel at the bottom, but it will be supported off something more substantial than that short piece of timber.
(Clearly a hip-to-gable conversion, but not sure about the way the rafters have been extended lower down? Doesn't look as though there's a purlin going in?).

 

[Jon6838]

Yeah I noticed the rafters too, not sure what’s going on there. With regards to the ridge beam, you can see at the bottom right of the pic (just above the guys head) that there is another stud (probably doubled up) so this I would imagine will have some sort of top plate between the two doubled up studs with the beam resting on that. But it seems that there are no studs directly under the beam itself? Would this be simply to spread the load a bit? I’m also wondering why they would attach these horizontal pieces of timber, if the beams are indeed resting on the studs/footplate, what purpose are they serving?
Sorry about the bad pic but it’s honestly the only one I could find with steel in a timber frame loft situation!

 

[tony1851]

I imagine there will be a doubled-up stud just to the right, with a short timber bridging piece - such as a couple of 4x2s - spanning between the studs, so that the load from the ridge is spread over two pairs of doubled studs. This arrangement would be more stable than trying to sit the steel directly on top of the doubled studs.
The distance between the pairs of studs would be quite small - say 300-400mm, and a timber bridging piece would easily span that. The piece on the front is probably intended just to tie the studs together

 

[Jon6838]

That makes more sense to me. Would the timber footplate be sufficient to cope with this load under the two sets of doubled up studs. What I mean is, as the weight of the beam is now being applied down through the doubled up studs to the footplate and thus to the timber frame on first floor, should the footplate also be doubled up to spread the load onto the frame below?

 

[tony1851]

I would guess that the studs forming the new dormer cheek (including those supporting the ridge beam) will be set on the original wallplate, which will be sitting (usually) directly on top of the inner skin of brickwork.