Please help! We've built a shed 25' x 13'. Rained a lot of the construction time. Concrete base. Sides of shed brick to about 3' depth outside. Inside are breeze blocks, polystyrene sheets in between br.blocks and bricks to same height/depth. Damp coursed. Above this is shiplack timbers. Arched roof, properly doubly felted & bitumened and watertight. Problem, the plywood boards inside the roof continue to become damp. Inspite of trying to dry out with dehumidifier etc. Doors double glazed and windows which we open when suitable weather arrives. How can we get this building dry for ever! We fear that it will continue to become wet ad infinitum (already mouldy).
Newly Built Shed: Dampness in Roofing Panels - Help?!
- Thread starter Wendi
- Start date
Sponsored Links
not sure what you mean.
Is this under the felt and on the underside (room side)? If so it is probably condensation. Concrete is made of water (plus cement and ballast) and so are brick walls, so until they have finished drying off they will give off a lot of moisture. if the ground slab has no DPM it will let water through for ever.
You have to ventilate a lot more. If you don't want to leave the windows open, put in some air bricks or other vents on all sides so you get a through flow of air.
If you are using heating inside the shed, then you are generating warm humid air, which will form condensation on the first cool surface it meets.
So if it is going to be heated you need an insulating layer sealed off on the warm side for penetration of warm damp air from the room to the loft, and to ventilate the "loft" area separately from ventilating the "room"
The structure may take months to dry out properly, and while the moisture is evaporating from the floor, its condensing on the roof.
And even once dry, if you have not insulated the roof, the plyboard will continue to suffer condensation.
You should have constant, permanent ventilation, and just opening the windows now and again is not helping much at all.
Consider fixing some rigid insulation to the underside of the roof deck
And even once dry, if you have not insulated the roof, the plyboard will continue to suffer condensation.
You should have constant, permanent ventilation, and just opening the windows now and again is not helping much at all.
Consider fixing some rigid insulation to the underside of the roof deck
Thanks to both repli-ees. Understood, but when it eventually dries out, what is the best way to insulate the inside plywood roofing panels. Thanks in advance.
Sponsored Links
Wendi (previous question about damp shed boards inside newly built shed) would still like some ideas as to how to insulate the roof inside. Polystyrene? That is when it eventually dries out. Ideas please gents.
you can get rigid insulating boards in the DIY sheds, with an aluminium foil layer on both sides, Celotex or similar. that would be easy to fit as you can screw it to the roof battens which will leave an air space above the insulation and the roof (ventilate this space to the outside with a few holes to prevent condensation).
it is a bit soft to use on the walls as it dents easily if knocked, unless you have a ply lining.
it is a bit soft to use on the walls as it dents easily if knocked, unless you have a ply lining.
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
