Not another garden shed posting!

[GNRi1959]

I was hoping to get some feedback on modellers who are currently working in garden sheds, whether modelling or storing layouts. As you know I have a new shed in place and just yesterday someone suggested that since I don't have a vapour barrier on the outer shed framing I would get mould and dampness inside my shed cavity.

 

Basically, the shed is high quality tongue and grooved boards on a 3" framework. The roof is felted over the timber rafters and PVC coated corrugated tin on top. I have filled the void in the walls with Rockwool insulation and sheeted the inside with Smartply.

 

Has anyone with experience or knowledge in a similar situation got any comments to add on whether I will have problems further down the road. Please.

 

Thanks

[Broithe]

A vapour barrier can work both ways. If you're spending a lot of time in there (and breathing), then you need to consider how that moisture gets out.

[murrayec]

Hi Tony

 

A vapour barrier and ample ventilation is a must, the barrier is to protect the insulation from condensation from the inside, as Broithe says- breathing and heaters, the barrier is placed inside the insulation to stop condensation going up through the insulation, condensing on the inside of the outer skin and then dripping onto the insulation. Roof and walls should have vapour barriers. Air gaps between the insulation and the structure is a good idea also....

 

Cross ventilation should be installed in the walls so that air can circulate through, ideally at each end of the structure and ample size.

 

Eoin

[GNRi1959]

Eoin and Broithe, thanks.

I cannot fit a vapour barrier on the outside skin as the shed came sheeted. I put insulation into the studs and sheeted the inside with Smartply. Should I remove the ply and fit a barrier to the inside skin? Is there any point at this stage. I will be putting a vent at either gable end of the shed tomorrow and as you can imagine, shed doors are never totally airtight.

[murrayec]

Hi Tony

 

Yes, remove the ceiling ply and install the barrier on the inside of the insulation only, it is for stopping condensation from the inside getting into the insulation- damp insulation is no insulation and if you keep breathing it wont dry out! Do at least put it into the roof, walls less important but best to do it...

 

Eoin

[Broithe]

Eoin and Broithe, thanks.

I cannot fit a vapour barrier on the outside skin as the shed came sheeted. I put insulation into the studs and sheeted the inside with Smartply. Should I remove the ply and fit a barrier to the inside skin? Is there any point at this stage. I will be putting a vent at either gable end of the shed tomorrow and as you can imagine, shed doors are never totally airtight.

 

The vapour barrier should be on the inside of the insulation, I believe, to stop internally generated water from condensing into the insulation, when it reaches a suitable point in the temperature gradient.

 

As above - the roof is where the warm (moist) air will congregate.

 

I suspect that, if you are just breathing in there and not boiling kettles or using unflued combustion heaters, then you may well be OK as it stands.

 

The vents, for a reasonable bit of air-change, will definitely help.

[murrayec]

[GNRi1959]

Eoin, the roof has a breathable barrier on the outside under the PVC coated tin. Its the only part with a barrier. So go ahead and do walls? There will be no kettles, radiators or otherwise.

Edited October 5, 2017 by TonyMcGartland

[murrayec]

Hi Tony

 

Did you install the insulation in the roof after the shed was erected? & is the roof insulation below that breathable barrier? If so it's not a vapour barrier and you should install one below the insulation. Study the drawing above

 

Eoin

[GNRi1959]

Hi Tony

 

Did you install the insulation in the roof after the shed was erected? & is the roof insulation below that breathable barrier? If so it's not a vapour barrier and you should install one below the insulation. Study the drawing above

 

Eoin

 

Eoin, the roof has no insulation at all. It is made up of four trusses, a breathable roofing felt and PVC corrugated tin on top. I have counter-battened the underside of the rafters and collar tie to give me sufficient grounds to screw 12mm smartply directly to the battens.

[murrayec]

oooooh Tony

 

You got to put insulation in the roof! or you will never be able to keep the temperature up- your poor models and layout would suffer, not to mention you in the depths of winter, the roof is 70% of the area that you loose heat thru.....

 

The reason the shed guys put that sheet under the tin roof is to drain away the condensation that forms on the underside of the tin and drips down! It's actually a draining sheet, if you look closely the holes are perforated from inside out which allows the drips to slide away to the sides and not drip on top of you....

 

Humidity is the bitch! an non insulated shed is about 10% less humid than outside, moisture comes up through the structure and condenses on anything cold like a tin roof and then drips

 

Eoin

[GNRi1959]

Eoin, lets get this correct once and for all.

Tomorrow I go down to the builders yard and get heavy roll of polythene damp course sheeting. Remove the Sterling board and tack the polythene to the inner walls of the shed. Replace the sterling board. Then insulate the roof, cover the inside with polythene and replace the Sterling board? Is this correct.

 

I take it the Polyethylene barrier you refer to is similar to heavy gauge builders polythene sheet on a roll?

[murrayec]

Hi Tony

 

Yes, you have the sequence right, the polythene sheet goes on the inner walls covering the insulation, then the ply goes back on. It does not have to be heavy gauge, most suppliers have a light sheet for vapour barriers. Most important is to ensure the sheet is not damaged and has good overlap between the ceiling and wall sheets. Fixing the ply on can damage the barrier with the fixings so a bead of TEK7 along the studs on top of the polythene staples before offering up the ply will seal the holes of the fixings.

 

Put as much insulation in the roof as you can, more is best

 

Take a look at these images, which may help;- https://www.google.ie/search?q=vapour+barriers&client=firefox-b&dcr=0&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiRuay8qdrWAhWHtBoKHXjSAusQ_AUICigB&biw=1280&bih=892

 

Eoin

[Mayner]

Hi Tony

 

Personally I would not fit polythene as a vapor barrier between the framing and Stirling Board as its likely to trap air moisture breath and environmental) inside your shed and potentially increase rather than decrease the risk of molds and damp inside your shed.

 

In recent years building design has shifted away from vapor barriers towards building wraps such as Du-Pont Tyvek or bitumen based "building paper" that allow airborne moisture to enter and leave a building following problems with leaky homes in North America and New Zealand.

 

The Stirling Board and roofing felt will serve a similar function to a building wrap.

 

I would strongly recommend insulating the ceiling and laying polythene on the ground underneath the floor. The polythene will prevent moisture from beneath the floor approx 3ltr a day for a 9Sqm shed https://www.standards.govt.nz/touchstone/building/2014/jul/preventing-dampness-under-suspended-floors/

 

 

I live in a 1920s renovated bungalow of timber frame with weatherboard wall cladding and a corrugated iron roof similar to your shed, with similar range of temperature and humidity to the West of Ireland.

 

Although our walls are not insulated and no vapor barriers/building wraps used, mold and damp is not an issue

 

1. the important thing is to ensure adequate ventilation at eaves level by leaving a gap between the top of the insulation and the underside of the roofing felt at eaves level.

2. Ensuring that the temperature inside the shed does not fall below dew point.

 

I have an electric radiator with the thermostat set at the minimal setting in my garden shed/workshop which is of similar construction, and have had no problems with moisture damage to tools rolling stock or electronic equipment

 

Gyproc Thermaline http://www.british-gypsum.com/products/gyproc-thermaline-pir?tab0=0 or a similar insulated plasterboard is probably the simplest and most economic way of insulating the ceiling in your shed.

Edited October 6, 2017 by Mayner

[GNRi1959]

John, I welcome your message and am only too glad that it arrived before I started any further work. My father was a Carpenter all his life and believe it or not, I am also a Carpenter who teaches in our local College. Now anyone reading the recent posts may think that it's time I hung up my boots and retired from teaching if thats the sort of questions I am firing out to a modelling forum. However, recently the country has gone mad on 'air-tightness', 'super-insulated', 'passive housing' and 'thermal bridging'. Whatever happened to good air circulation around a building? My fear is that introducing polythene barriers will promote sweating and more moisture and although Eoin is correct to direct me towards architects details on the matter, these details are fine in housing but not necessary in small garden shed. I'm in two minds about the vapour barrier but I will certainly insulated the roof.

[Portoman]

Tony, I just got a shed 16 x 12 with the intention of moving my layout from the attic. It will be 12 x 12 on two levels. My shed is tongued and grooved with breathable membrane on the walls . Ceiling is OSB with felt. I lined both walls and ceiling with 25 mm insulation boards between joists and covered with 6mm ply. There are gaps for air circulation. You can lose the plot if you read everything you should do. I never had problems in the attic and it hadn't got as much insulation on ceiling. Dave

[GNRi1959]

Dave, my first layout was in an attic with little or no insulation. It was fun.

Sometimes we get very protective of our hobbies and interests, on this occasion all the advice received was valid however theres always a cut off point when it comes to most things.

[GNRi1959]

Last night the electrician installed an armoured cable and connected the 'Dundalk Works' up to the power supply so I now have light and sockets. Today I started finishing the ceiling and laying nice 32 x 9mm redwood slips over all screw heads on the uprights, gives a sort of 'panel effect'. Things are progressing, I do a bit everyday, that way you enjoy it more!

 

 

Edited October 13, 2017 by TonyMcGartland

[GNRi1959]

Tony, I just got a shed 16 x 12 with the intention of moving my layout from the attic. It will be 12 x 12 on two levels. My shed is tongued and grooved with breathable membrane on the walls . Ceiling is OSB with felt. I lined both walls and ceiling with 25 mm insulation boards between joists and covered with 6mm ply. There are gaps for air circulation. You can lose the plot if you read everything you should do. I never had problems in the attic and it hadn't got as much insulation on ceiling. Dave

 

I'm fitting two 9x3 vents to either gable today, so that will also help. When I'm in the shed I usually have the door open all the time!

[dave182]

I'm looking out the back window here one last time to make sure everything is tied down before this hurricane thing hits, and what pops into my mind? Tonys new shed!!! After all your hard work I hope you thought to put a few bolts in the ground! Stay safe out there lads and Tony, I'll say a prayer to St. Theresa (Mannion) for the safe passage of your shed through Monday!

[Broithe]

I'm looking out the back window here one last time to make sure everything is tied down before this hurricane thing hits, and what pops into my mind? Tonys new shed!!! After all your hard work I hope you thought to put a few bolts in the ground! Stay safe out there lads and Tony, I'll say a prayer to St. Theresa (Mannion) for the safe passage of your shed through Monday!

 

[DiveController]

Better now than when the layout is in it! That would be soul destroying.

[GNRi1959]

I appreciate your prayers lads but please save them for the countless of homeless people around Ireland today who don't have the luxury. I was in Dublin a few weeks back for the Albert Hammond concert and was staying at the Hilton Hotel (special weekend deal). On the Sunday morning I was out for a nice walk when I came across a young lad, maybe 17yrs old sleeping a phone box. He had obviously spent the night there.

 

Hy lads, I do see the funny side of your post too

[GNRi1959]

No casualties in the garden apart from a large broken branch on an older tree, shed still there!

[Broithe]

No casualties in the garden apart from a large broken branch on an older tree, shed still there!

 

Phew!

 

We can breathe again...

[WRENNEIRE]

Was hoping for this myself, bit of divilment!

 

[GNRi1959]

Christ, you's are great craic!

 

End of Thread