Existing building frame retrofit

[ColdOutside]

Hi,

 

I have an existing lean to outbuilding, sloped slate roof chased into third party large stone wall and then 3 sides coming off it made of half brick and wood construction. The wood is currently rotten but 1m height brick wall seems solid with underfelt etc so going to strip roof and rebatten and reroof and then replace the wood framing.

 

First time using sketchup but the attached will sit on existing brick wall. 

 

Anyone see any issues? Using 16" centers but gable a little more made up to offset window slightly.

 

Footprint is 3190mm x 1920mm.

 

 

[ColdOutside]

The reason for only 2 sides is back long wall is stone as above but bottom end is a self contained brick built outdoor loo with door between last stud and loo. As such I think this is the only framing I need to do bar the awkward triangle bit above the gable window (bit advanced for my sketchup skills)

[ColdOutside]

Some more context.

[ColdOutside]

I'm actually planning to rain screen the entire building, so as I'm putting 11mm OSB onto the stud only, would it be wise to inset the stud wall be 11mm on both sides so that the clad battens go top to bottom without an 11mm spacer on the brickwork?

Edited December 29, 2023 by ColdOutside

[Russell griffiths]

That sketch is very basic. 

It could be that’s just how you have drawn it up. 

 

For instance look at the corner and work and work out how your internal wall covering will be fitted

the way it is drawn you do not have a stud to fix to, externally you do but internally you don’t. 

You normally do a two stud corner to turn a 90 degree, or if you want to insulate it you do what’s called a California corner. 

 

Setting it in 11mm sounds like a plan, don’t forget a weather barrier to the outside under the battens. 

And some sort of insect barrier to the batten area. 

[ColdOutside]

Can you confirm how it's basic? Only missing noggins, right? Roof structure not required as making good with what's there.

 

You're right about the missing stud on this nearside corner for the internal OSB. I forgot to add really. I was planning on doing a 90 degree stud so the gable wall can fix onto and also the internal OSB. Would there be a cold spot in the corner as I plan to use 90mm solid insulation so this will not wrap around the 90 degree stud?

[ColdOutside]

Yep, got a UV/black membrane to go on, as it's an open rain screen it'll be visible, so a bit pricey. Also, if it's already an open membrane, no point having a insect barrier is there?

[Russell griffiths]

California corner, allows insulation into the corner, if that’s what you need. 

Frame not connected at top plate, so either a double top plate or the plate holding the roof up will do. 

Without seeing the rest of it it’s hard to tell, probably immaterial if it’s just a bit of an out building it’s probably fine. 

 

[ColdOutside]

So I'm slotting the frame under the existing top plate which holds the roof joists, hence why I've not done a double as it runs the whole length of outbuilding.

 

I'm trying to do stuff properly, but I am a complete novice so welcome as much advice as possible. It's an old lathe workshop that I'm turning into an office.

 

Edited December 29, 2023 by ColdOutside

[ProDave]

Why 16" centres?  400mm or 600mm

[ColdOutside]

Complete novice getting mixed up with imperial and metric I suspect.

 

If I'm using 2x4 at 1.5" x 3.5" then surely I have to mix metric and imperial? My OSB above still lands bang on center line?

Edited December 29, 2023 by ColdOutside

[ProDave]

Your "2*4" will actually be 195 * 47mm

 

Be careful.  OSB sheets are available in 8ft by 4ft or 2400mm by 1200mm.  As far as I know (someone tell me if otherwise) plasterboard is only available in 1200mm wide not 4ft, and usually in 2400mm long not 8ft (though can be bought in longer sheets)

 

16" is 406mm.  So over 3 studs that will be 1218mm.  By the second or definitely third sheet of plasterboard the joints will miss the studs.

[ColdOutside]

Do I just forget about imperial then? I shouldn’t be mixing?

 

 

[Russell griffiths]

Depends if you can get metric osb, if you can then build it to metric sizes. 

Its the arse about face country we live in. 

Trying to embrace the future while being firmly stuck in 1868. 

 

Have a good read up on your choice of open rainscreen cladding. 

 

I personally would avoid it, unless it’s a design you are really looking for.  

[Russell griffiths]

How are you planning on insulating the brick wall. 

That might influence how you build the stud wall. 

[ColdOutside]

Yep would rather do full metric, my mistake really for not questioning it.

 

Read a lot about open rainscreen. I can’t really see any reason to avoid? Building position is not particular open to elements and I like the design of it over block on block. Still may change mind but I’m after this design.

Not decided on insulation for lowers as there is already a timber skin inside which I haven’t removed to see what’s behind. 

 

 

[Russell griffiths]

I haven’t done it myself, I went with a shadow gap cladding 

but have a search on here, I remember the downside being cost, the timber needs to be high quality to maintain the look, the membrane is expensive, and I think people experienced it getting eaten by wasps. 

 

I have a lot of wasps and always wonder what what they are chewing to make the nest, I’ve experienced having holes bored through my facia boards, so that membrane would be my big worry. 

I did look at a membrane that stuck on to the racking boards and preferred that to the version that is only fixed under the battens. 

[ColdOutside]

I was actually half opting to save costs as less clad material in theory, due to gaps.

 

1 roll of this — https://www.ecologicalbuildingsystems.com/product/solitex-fronta-quattro ~£400

70mm clads * 85 — https://www.timberulove.co.uk/products/siberian-larch-charred-cladding-battens-a-grade-22mm-thickness-square-edge/?attribute_dimensions=20+mm+x+70+mm+x+3000+mm+-+£13.73 ~ £1.1k

 

£1,5k total for clad, plus the little extras.

 

Can the above look be done cheaper? Think it's roughly 20sqm.

[Mr Punter]

1 hour ago, ColdOutside said:

Can the above look be done cheaper? Think it's roughly 20sqm.

 

Yes, you could do it in natural slate.  Won't fade or warp and will last longer than most of us.

[ColdOutside]

Not sure natural slate would really resonate with a black timber vibe.

[oliwoodings]

I'd definitely think about your brick insulation first before deciding on the timber frame above. Could impact the design of the frame.

 

Check out Hardie Plank VL for the cladding, you can do vertical with it, they have it in black, very sleek.

[Iceverge]

On 29/12/2023 at 23:03, ColdOutside said:

Do I just forget about imperial then? I shouldn’t be mixing?

 

 

 

Yup, buy a metric only tape too. It'll make your life much better. 

[ColdOutside]

7 hours ago, oliwoodings said:

I'd definitely think about your brick insulation first before deciding on the timber frame above. Could impact the design of the frame.

 

Check out Hardie Plank VL for the cladding, you can do vertical with it, they have it in black, very sleek.

Thanks for clad rec.

 

I don’t see how stud design will change? If I use say a 50mm solid insulation on wall it’ll just give me a ledge internally which I’m ok with as need the space really.

[oliwoodings]

8 hours ago, ColdOutside said:

Thanks for clad rec.

 

I don’t see how stud design will change? If I use say a 50mm solid insulation on wall it’ll just give me a ledge internally which I’m ok with as need the space really.

If you're fine with a ledge then crack on! 50mm battens on the brick, fill between with PIR, vapour barrier over the top and then plasterboard. You'd probably want to bring up the brick battens & insulation so it overlaps the timber frame a bit to avoid cold bridging in the corner of the ledge.

[Mr Punter]

19 hours ago, ColdOutside said:

Not sure natural slate would really resonate with a black timber vibe.

 

Have a look at some:

 

https://www.cupapizarras.com/uk/news/slate-cladding/