Timber extension- structure q's.

[zoothorn]

Hi chaps,

 

[edited/ changed]

 

I've got a quote for a timber framed extention, but need help on structure basics.

 

Design simple: a workshop 'box' below, & 'study' above. Footprint ~4x4m. Pitched roof, window, french windows, knock-thru door to study (from bedroom). Box below only 1 door to outside. That's it, cannot be simpler.

 

My quote includes external wall & stud work: idea is builder to get watertight > me to line insides to ££save alot (heat insulation in 'study', sound insulation in 'box') . My kitchen was ideal project to practise.

 

What I can't get my head around is how the upper floor/ roof is supported: what might consitute the 'external walls' for the study above + roof to be supported/ built ontop? I thought the upper story/ roof weight goes onto -internal- walls, & the outer wall is then put on around it.

 

The other thing is the 'cavity'. I assume the study above would need one if warmth/ a house room is the idea: but the workshop box below is different- I don't need warmth & want as simple a structure as possible (1 course of block ideally but builder recommends timber to get my quote down). So if I have external walls built > I add studs > soundwool > pB. But can I do this? or do I have to have a 'cavity'? I cant get my head around what the studs attatch to.

 

Thanks,  zoot.

 

 

 

 

 

Thanks, zoot

 

 

 

Edited May 2, 2019 by zoothorn

[zoothorn]

Hi chaps- maybe I haven't made any sense. I'll rephrase my questions..

 

What is a timber-frame construction? the name implies the -frame- is timber, but not what the walls are made from. What exactly constitutes the 'frame' anyway?

 

In order to establish if I can do any of the build myself, I need to 1st understand the basics of how such an extention is made. Ie, how a 1st floor timber-frame room is built onto a timber-frame ground floor room below.. Ie if the walls are not made from block, how is this 1st floor & roof sufficiently supported?

 

Can anyone help? thanks zoot.

[Simplysimon]

timber frame is 145x44 regularised timber, this will consist of four frames joined together at the corners, joists will be laid across box and anothe four frames the same as below will be placed onto joists, frames clad with osb. a brick skin can then be built up the outside and attached using wall ties fixed to osb. roof on the top and upper floor insulated between studs and between joists.

simples.

 

https://www.kilbroneytimberframe.com/timber-frame-housing from a quick search of 'timber frame walls' and images

Edited May 8, 2019 by Simplysimon
adding web link

[zoothorn]

Thanks simon. Great link/ gives me many answers.. but one remains nagging. On a traditional build, is it right that 2 courses of block with a cavity are the norm, the roof joists laid across the -inner- course. Which is the same for the timber frame eg/ info here.. bar just the inner course, which is made from timber onto which the roof load sits-?

 

If so I can't see much difference between the two, apart from a lesser weight & material cost, of solely the inner course. Is that correct? If so I can't see how "timber frame" builds are deemed so different & coined as a separate 'method' of building at all.

 

You see I'm waiting on a quote from builder who suggests 'timber frame' to reduce my estimate, but I don't know whether he'll be using a block outer course or not.. so meanwhile (a huge wait, as per normal, for his estimates) I'm best not pestering him on these basics & just crack on & find this info out myself.

 

 

 

[Simplysimon]

the main difference is that timber frame can be built no matter the weather, cold/wet/frozen you can build timber, blocks cannot be built if the temp is too low. should be able to have a better u-value for the same thickness of wall with timber. more chance of a diy build with timber than block.

separate 'method' due to a 'traditional' build being done by brickies as opposed to joiners. the brickwork trade is being marginalised/superceded by other build methods and a reduction of skilled tradesmen unless they are building facing brick  and therefore those still building with brick/block wish to keep that method for self preservation, understandably. 

[zoothorn]

Many thanks Ssimon (had thought no replies/ no usual prompt happened, hence just seen reply).

 

Ok understood. So, if my builder has specified TF build, as seems to be the case.. Im trying to establish what then comprises the actual substance my walls will be made from. Apart from "FFS- wood u dummy!" as an answer.. you see a brick course, in your diagram link suggests this is part of a TF build. Or is it? or if not, it would likely be replaced by specifically what exactly?

 

You see I need to establish how my walls will be constructed. Out of what material. This is SO massively important for 2 reasons:

 

1) solidity- the end of my house is the most targeted for weather of any house in the village, elevated a bit & end of a small valley that narrows.  I need to establish if a TF build, whatever exactly this means (Im still not sure if it comprises brick or not) will be strong enough.

 

2) how much, if any, of the build I could feasably do myself to reduce my costs.

[zoothorn]

.. and 3) I need to establish the wall material to know what the sound-proof 'properties' of my lower room is too.

 

Can anyone tell me how a 1st floor & roof is supported on a TF build? if it were a block, the joists span the 4 block walls (of the ground floor in my case) .. the load so my logic states, pushes evenly down thru the solid walls' structure. But TF have no solid walls.. so how is a load above supported?

[the_r_sole]

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Edited September 26, 2019 by the_r_sole

[zoothorn]

The r-sole (!)..

 

ok great that gives me a bigger picture of what my TF build's structure.

 

But what about the actual wall material? I just cannot visualise what consitutes the "meat" of a TF wall structure, which would replace the "meat" of a solid/ denser, brick or block wall construction (especially so if you're confident the TF build is 'no less solid').

 

And why is the word FRAME used? if I could see an eg of some sort of heavy-duty, solid-wood maybe, metal-bracket-braced "frame".. onto which xyz wood additions are added.. the word would make total sense & clarity. But I see no such thing, &, confusingly, the above image of a TF wall construction.. has a brick course within it.

[the_r_sole]

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Edited September 26, 2019 by the_r_sole

[zoothorn]

Thanks for the link- that really helps with the construction Q's. How its a 'self-build' Im not quite sure (seems morelike an advert for a specific build Co) but now I have an overall picture of the way a TF building's made (so the outer brick in eg above.. is on optional cladding situation- ok!).

 

I think I need to to another thread on build steps > to see how to minimise costs of my humble extension. I'm still overbudget, but with careful planning & advice, & using the skills I have.. I hope I might just be able to be afford it.

 

Terrific info mr. 'sole thanks!