shed insulation

[jack55]

Hi when I did mine I put a waterproof breathable membrane on the outside then the cladding. Then on the inside stuff the walls with cheapo loft insulation, followed by a vapour barrier covered over with 6mm OSB. The floor has 18mm chipboard T&G 2" polystyrene and another layer of 18mm chipboard T&G. Its nice and warm in winter and cool in summer.

 

[fraser]

Will that not still attract condensation to sit on the barrier and make the ply wet rather than the roof?

 

[jack55]

Will that not still attract condensation to sit on the barrier and make the ply wet rather than the roof?

the barrier is breathable and you ideally leave an air gap between it and the outer layer.
the barrier is on the outside then the cladding, here the batterns allow an inch air gap between the barrier and the cladding.

Inside the walls are insulated

Then a vapour barrier

The roof is the same

Insulation in this case 4" polystyrene then a breathable barrier then boarding then felt then roofing material.

Between the insulation and the barrier is a 50mm air gap vented at the eaves

 

[chaletview]

I have an 18' x 15' shed with a 1 meter high apex roof.
I have had it about 5 years and would now like to turn it into a studio of sorts.
I have read all the previous posts and have created a chart which encompasses the essence of what a number of you have suggested.
Does my interpretation seem reasonable?

My main lack of understanding is condensation.

I would welcome anyone's views on this.

Thank you

PS I would have preferred to show the diagram in the main body of the text but couldn't work out how to do this. Sorry.

 

[Dibs-h]

A few things -

1. I wouldn't use polystyrene. Whilst it it is better than nothing, if it catches fire - screwed is putting it politely.
2. I would rather line with ply - it adds some rigidity and all importantly security. & no VOC's or whatever mdf gives off. and should you have a leak (water penetration), ply is far more tolerant.

HIH

Dibs

 

[Lons]

Think of the Roc slab as dense firm loft insulation. It isn't solid but has definite shape and form which means you can install it vertically in wall voids etc. IIRC I got mine from Jewsons about 6 years ago.

All the builders merchants stock it but what you should ask for are "cavity wall bats". they are available in several thicknesses to suit the internal gap of a cavity wall, are sold in packs of several M2 9dependant on thickness. (just done a quick google and this is the first linlk http://just-insulation.com/rockwoolcavity.html ). I buy mine from Jewsons.

They are more expensive than loft insulation but made to withstand moisture, have more sound absorbing properties and are self supporting - don't sag.

Cellotex type sheet is the alternative but more expensive. Even easier to handle just mind the dust when you cut it - even with a knife - plays havoc with my eyes :roll:

Bob

EDIT...... NOTE TO SELF - READ ALL THE PAGES NOT JUST THE FIRST ONE BEFORE POSTING YOU D******D

 

[MARK.B.]

No expert Chaletview but would it be wise to glue the tarpaper to the shiplap ?,any movement in the wood could potentially tear it.Maybe put a layer of ply/osb and put the shiplap on that (10mm thick shiplap imho may not be strong enough).

 

[billybuntus]

I've used 100mm cheap loft insulation stuffed into a 75mm void with a heavy poly sheet over it as a vapour membrane (non breathable. Lined out with 1/2 inch mdf as it was free (coated the mdf in clear would preservative then painted with white undercoat).

No problems with it at all and it keeps the heat in immensely well.

 

[giantbeat]

i am using wicked general purpose insulation slabs in the roof on my workshop, decent thermal insulation & noise reduction, currently on offer @ £26.69 a pack which covers 7.2m2 which came up good value from what else i had found, the fact that is literally a 30 second walk for me also sealed the deal.

 

[chaletview]

Many thanks for getting back to me. I assume the rest of my chart is OK?

 

[chaletview]

I drew up the diagram as I had read through all the previous posts.
As some of them are old I just wanted to check if this was the current way of insulating a large shed.
Thanks to giantbeat and billybuntus and MARK.B. for your helpful replies.
As a newcomer I appreciate the hand holding.

 

[chaletview]

Hello GIANTBEAT, if the gap is 70mm deep, should I get filler to fit in exactly or leave a gap?

 

[buffalobill]

Hello GIANTBEAT, if the gap is 70mm deep, should I get filler to fit in exactly or leave a gap?

You should fill it , should not be a gap between the insulation and the vaporbarrier.
Rockwool and others have many diffrent 50,70-100,150 and thinner and thicker

 

[beech1948]

chaletview,

You got it almost right. The structure of the walls should be :-

0) Seal up all small gaps in the structure
1) Outer cladding...NO tarpaper against it at all
2) 25mm air gap. Achieved by putting roof tile laths or similar nailed down the studs and then later nailing the cladding across these
3) Breathable outer membrane eg Tyvek wrapped around the stud frame
4) Insulation of choice
5) Vapour barrier with all edges and overlaps taped up and together to form an impervious barrier including taping over all staples or nails
6) An internal wall layer which could be plasterboard, ply or OSB. OSB is about 60%+ resin glue and could be regarded as a solid barrier. It can be painted white easily and is cheap.

Now your construction did not follow this as you initially missed out on the external air gap and the breathable membrane and maybe you did not close up all of the small gaps.

I don't know where the water is coming from in your roof but finding that leak and closing it seems like a first step.

I assume you have felted the roof. I am less than certain that felt is good enough for a workshop. You may want to cover this over with say ONDULINE with use of the eves and roof ridge panels to provide a solid and waterproof roof. Onduliner is easily available and fairly cheap. Its a panel made from bitumen like resinous layers and has a wavy appearance.

Having dealt with the roof you may want to stop there and see if you have any other leaks from the walls...if it seems OK then enjoy.

All of this was discussed many times a few years ago but as a newcomer you may have missed these posts. Search for Mike Garnham
and workshop builds as he was the undoubted master of workshop construction.

Hope this helps

Al

 

[chaletview]

Thank you beech1948 for your comprehensive reply.
Just to be sure can I just mention that I have a large shed 18' x 15' which has been in situ for 5 years or so and in good condition.
I now want to insulate it. It does not leak.
The key features are that the construction is of 10mm thick shiplap X 120mm wide - again all in very good condition.
The stud frame is 70mm deep by 35mm wide. The gaps between the uprights is 560mm in the main.
I was thinking of buying the thermal insulation & noise reduction, currently on offer £26.69 a pack which covers 7.2m2 from Wickes suggested by giantbeat.
However that is 50mm thick so arguably there would be a gap of 20mm. Should I go for 75mm thick and will it 'stand up' between the uprights.
How should I attach the insulation to the inside of the shiplap?

 

[giantbeat]

Thank you beech1948 for your comprehensive reply.
Just to be sure can I just mention that I have a large shed 18' x 15' which has been in situ for 5 years or so and in good condition.
I now want to insulate it. It does not leak.
The key features are that the construction is of 10mm thick shiplap X 120mm wide - again all in very good condition.
The stud frame is 70mm deep by 35mm wide. The gaps between the uprights is 560mm in the main.
I was thinking of buying the thermal insulation & noise reduction, currently on offer £26.69 a pack which covers 7.2m2 from Wickes suggested by giantbeat.
However that is 50mm thick so arguably there would be a gap of 20mm. Should I go for 75mm thick and will it 'stand up' between the uprights.
How should I attach the insulation to the inside of the shiplap?

you should not need to attach the inuslation to the shiplap matey, you can cut the insulation sightly larger than the gap between the studs & push fit in so its wedged in place.

i have never insulated a shed but am insulating my cellar ceiling, I'm just cutting the insulation 2-3cm wider than i need & pushing it in place, it compresses uneasily & holds its self in place very solidly.

You should have no issue doing what you are wanting, the instructions for fitting it between studs are on the insulation instructions, if you read the reviews from the wicked site people have used it for all sorts of things.

 

[beech1948]

Thank you beech1948 for your comprehensive reply.
Just to be sure can I just mention that I have a large shed 18' x 15' which has been in situ for 5 years or so and in good condition.
I now want to insulate it. It does not leak.
The key features are that the construction is of 10mm thick shiplap X 120mm wide - again all in very good condition.
The stud frame is 70mm deep by 35mm wide. The gaps between the uprights is 560mm in the main.
I was thinking of buying the thermal insulation & noise reduction, currently on offer £26.69 a pack which covers 7.2m2 from Wickes suggested by giantbeat.
However that is 50mm thick so arguably there would be a gap of 20mm. Should I go for 75mm thick and will it 'stand up' between the uprights.
How should I attach the insulation to the inside of the shiplap?

I'm not an expert on insulation more a follower of Mike G's recommendations.

I would suggest that you use the batts of stiff insulation mean for brick cavity walls as these come in easy to handle sizes are fairly easy to cut.

I wouldn't attach to the cladding at all

I might consider adding a breathable membrane to the inside but I don't know for sure that this would work because they usually need the air gap to work best.

You could just use 2inch batts and place a lath between the batts and the cladding to act as a spacer and to give an air gap of 20mm.

Filling any and all gaps would be good to achieve with a foam gun is what I usually use.

Inner impervious membrane all taped up and then an outer wall covering of say OSB.

regards
Alan

 

[chaletview]

Many thanks to you all for your helpful suggestions.
I will digest this at the week-end and plan the installation.

I really am very grateful.

 

[will1983]

Chaletview, how did you get on? and did you take any photographs?

 

[Walnutt]

Hi, I'm new here but this thread has been of real interest.

I'm getting a 12x8 timber pent shed delivered on Tuesday for a general woodwork workshop and have the insulation lined up as per Beech1948's recommendations, hoping to have minimal damp / condensation.

Process is, from the outer to the inner..

13mm shiplap t and g (All studding frame gaps sealed).
25 mm air gap (with breather vents in each stud section top and bottom).
Breathable membrane.
Kingspan 43mm (seconds..).
Polythene vapor barrier taped (warm side of insulation).
11mm osb3.

Roof is vented at front and back and the same process is adopted but with 50mm air gap.

Shed has 3x2 bearers on paving flags and floor is 1" tantalized and I am thinking of adding a suspended OSB3 18mm with 23mm king span as follows from floor upwards.

1" tantalized floor
20mm air gap
23mm kingspan
18mm OSB3.
No ventilation in the sub floor sections....

I've read the Mike Garner posts / links and found them really useful. I'll be using stainless insect mesh to protect the air gap sections from bugs.

Also BS 5250 for control of condensation and associated free links are useful, as is Nhbc website.

I'm ok with the sides/roof, but not sure about the floor. Anyone have any thoughts?

Thanks.