Insulating summerhouse (during build)

[Stringman_uk]

Oriented Band Strord?

sorry my brain was in dfa mode (though I could play the dyslexic card....)

That's the max eaves height if within 2m of a boundary and measured from the highest part of the ground, so you can end up with it higher at one end if the ground slopes

Thats confused me ( not difficult at the moment) so is it not the top of the highest point of the roof? and I thought it was 1m from the boundry not 2 or is that something else? ( material) Stupid thing is I spoke to the neighbours and they just said yeah do what you want we dont mind

 

[robinbanks]

Let's work this the other way round. Where are you going to put the building with regards to the boundary and what shape is its roof going to be; flat, mono or duo pitch?

 

[Stringman_uk]

The building is about 3ft from neighbours fence ( I could make it 1m) its going to be a flat (pent roof) the plan is for it to be one building 15ft x 8ft which is divided (by partition wall) as shed (5ft x 8ft) and summerhouse- if that makes a difference. It could (at a push) be 2 separate buildings.

 

[noseall]

After lots of reading I am starting to worry that if I dont line at least one side with obs the frame will flex too much.

Correctly fixed sheathing will instantly prevent racking and should be a norm for all timber framed buildings. It only need be say 12mm though.

 

[Stringman_uk]

Thanks for your replies. I have realised that I will need to be closer than 1m to the boundry so I will need some "fire proofing"
I seem to remember that cement board could be used for that. could I use the cement board instead of the osb.
In fact on the back ( facing the neighbours) could i just use the plain cement board and paint it?

 

[mrrusty]

so I will need some "fire proofing"

You won't. You are under 15sqm internal floor area

 

[Stringman_uk]

Mr Rusty I thought it was needed regardless of size.

 

[mrrusty]

Is building regulations approval needed for an outbuilding? - Outbuildings - Planning Portal

Details of the planning permission and building regulation regimes for Outbuildings in England

www.planningportal.co.uk

 

[Stringman_uk]

mrrusty
superb thank you.
just wondering whether I could use cement board instead of osb or ply to sheath the frame ( or maybe just as a finish on the back?)

 

[robinbanks]

just wondering whether I could use cement board

To what end?

 

[Stringman_uk]

To what end?

The back end lol
Actually What i was wondering was for the rear of the summerhouse rather than fix osb sheathing , membrane, then baton, then fit cladding could I just membrane on the frame, baton and then cement board (would use building straps for first rigidity) then I could just pain the cement board?

 

[Notch7]

The back end lol
Actually What i was wondering was for the rear of the summerhouse rather than fix osb sheathing , membrane, then baton, then fit cladding could I just membrane on the frame, baton and then cement board (would use building straps for first rigidity) then I could just pain the cement board?

Yes, just paint the cement board

as you aren’t rendering, the joints will show, but that doesn’t matter.

if you don’t use some form of sheathing then the building will be less resistant to lateral deflection from wind load - maybe metal strapping used diagonally at corners would be a solution.

 

[Stringman_uk]

Notch, Many thanks for the reply.
Would the cement boards not to the job of sheathing as well as cladding? I would definitely use strapping as well.
I was thinking of using no more ply 18mm T&G to make the joins neater and stronger.

 

[Stringman_uk]

Revitalising this post with an update (and more questions)

The foundations are in, the wooden base laid (4" high 2"wide) and insulated and the sub floor (18mm osb) fitted.
I have cut the main timbers to size ready to fit the frame in place. The frame will be 4 x2 (4"wide 2" high)
I am sure that I read that the base of the frame should overhang the floor and the cladding do lower than the floor to protect it.
Is this correct?
If this is the case should I protect the edges of the osb to prevent damp? I do have spare waterproof barrier from covering the foundations.

I will be wrapping the walls on the outside in a tyvek type membrane can anyone recommend a suitable but cheaper alternative?

Finally earlier on in the post there was a robust discussion about installing a vapour check membrane, it seemed that it is not needed but could prevent noise and drafts so I will probably fit one. Is it just heavy duty plastic or is there some special properies to it.

Many thanks

 

[mrrusty]

So your framing up over a floor on a base. Yes, arrange it so that the cladding overhangs the edge of the floor, and yes, it is always a good idea to seal the raw edge of the flooring. The framing can be flush with the floor edge, but the battens under the cladding will allow it to overhang. I presume you are going to sheath the outside of the frame in thin OSB? in which case over that will go a breathable membrane. I recently used https://www.cwberry.com/protect-tf200-vapour-permeable-membrane which is a bit cheaper than tyvek and perfectly good enough for a summerhouse. This outer membrane on the cold side must be breathable. Over that goes battens to form a ventilation space, over that goes the decorative cladding.

Internally, assuming you have insulation in the framing a vapour control layer goes over the framing and under the internal finish. The vapour impermeable barrier stops warm room air getting in to the cold wall and causing condensation. https://www.cwberry.com/125mu-vapour-control-layer-27m-x-50m-green

For a fairly inexpensive and maintenance free cladding (particularly on external walls you can't see) painted metal is not expensive. https://www.cladco.co.uk/sheets/32-1000-box-profile-0-5-thick-polyester-paint-coated-roof-sheet they call them roofing sheets, but they work just as well on exterior walls. You can order them cut to length (because they are a PITA to hand cut). Shop around because different suppliers of cladco have different delivery charges. I have recently used https://www.roofingoutlet.co.uk/col...0-box-profile-sheeting-polyester-paint-coated