New Workshop Going Mouldy, Desperately Need Help!

[MikeG.]

That roof isn't strong enough. You've got a span of about 4.8 metres, so each rafter is spanning 2.4m. This needs to be done with 6x2s, which would also give you an air gap above the insulation. Obviously you need battens above a (breathable) membrane.

There could be ways of keeping the rafters as they are, but it will involve inserting sizeable principle trusses and purlins and counterbattening the outside before battening.

I feel for you. This is a lot of work going badly wrong in front of your eyes, and you've got lots of work to do to put it right. It's a pity you didn't find this forum 6 or 9 months ago.

 

[MikeG.]

...... ......

What are the ply packer things on the side of the rafters, and what is the plastic I can see behind them?

 

[MikeG.]

I know we do things differently over here but not too much.

Our framing is sheeted on the outside and the house wrap/building paper (breathable but sheds water) is stapled on the outside. Then depending on the kind of siding, battens or some kind of rain screen over the wrap with the siding over it........

That's the way it is done over here too, and it is wrong. I believe there will be a huge scandal in years to come as the shortcomings of this system are exposed. Ply and OSB are virtually impenetrable to moisture because of all the glue, so there is absolutely no point putting a vapour barrier over the top of them.......and having them on the cold side of the construction is nuts.

 

[Inspector]

That's the way it is done over here too, and it is wrong. I believe there will be a huge scandal in years to come as the shortcomings of this system are exposed. Ply and OSB are virtually impenetrable to moisture because of all the glue, so there is absolutely no point putting a vapour barrier over the top of them.......and having them on the cold side of the construction is nuts.

You may be right but the house wrap isn’t vapour proof but does shed water, much like the building paper (tarpaper) that we used to use. Actually still used by some. The vapor barrier is on the warm side.

The biggest problems are when water leaks inside the house wrap from poor construction detailing or workmanship and can’t get out. Then they mould and rot like there is no tomorrow.

I will say that here the OP wouldn’t have gotten a building permit without proper drawings with construction details. Nor would it have passed inspections by the building inspector at the specified points in the construction. He wouldn’t be facing the issues he has now.

In the morning I’ll read your threads on construction to see your way of doing things.

Pete

 

[MikeG.]

...... house wrap isn’t vapour proof......

No, but the OSB it is fixed to is. Therefore the vapour permeability of the house wrap is actually pointless.

 

[jimmy_s]

Short term iIf the shed is not heated then the permeability of the structure will be less of an issue I'd recon as there will be not much of a pressure differential driving moisture through the construction.

As a start, I'd get the thing ventilated to reduce moisture build up. Clearly there's a load of other issues as has been said already that you will need to deal with - if the weather ever improves.

You had better watch if it snows as your roof could collapse if you get a build up of snow on it. You might want to think about supporting it mid span onto the floor slab over winter.

 

[ColeyS1]

Buy a decent dehumidifier and drill a hole for the hose/water to drain outside. It's not an ideal solution but it should keep the mould at bay until you can find a better solution till money/time allows. Smart looking shed !!

Sent from my SM-G960F using Tapatalk

 

[crazySteve]

Well thanks for everything, looks like its game over for me.

-end of post-

 

[ColeyS1]

Sent from my SM-G960F using Tapatalk

 

[Nelsun]

I can only imagine how I'd be feeling were I in your shoes. Don't give up! You've obviously got the brains and skills to make a cracking workshop but have just missed some minor, bit ultimately hugely important, details. It's all too easy to do when faced with something new. Do not beat yourself up over it.

The folk on here are a wonderful resource to draw upon, and it's amazing how they give advice so freely to those that are willing to take it. Take a step back and come back to it once the swear jar has stopped filling.

 

[RichardG]

I second Nelsun’s comments, things are always fixable and you can sort this, just take a deep breath and start planning what needs to done. Use the clever people on this forum for ideas and solutions, you have some already.

I’m not a structural engineer but you “may” be able to fix the roof by adding some large purlins under the roof (where your double noggins are) and then support them on posts down to the ground. Sure this may not give you the open space you wanted but it may save you having to remove the roof. Only you can decide on what solution works for you.

So keep at it....

 

[RichardG]

I know we do things differently over here but not too much.

Our framing is sheeted on the outside and the house wrap/building paper (breathable but sheds water) is stapled on the outside. Then depending on the kind of siding, battens or some kind of rain screen over the wrap with the siding over it........

That's the way it is done over here too, and it is wrong. I believe there will be a huge scandal in years to come as the shortcomings of this system are exposed. Ply and OSB are virtually impenetrable to moisture because of all the glue, so there is absolutely no point putting a vapour barrier over the top of them.......and having them on the cold side of the construction is nuts.

I’ve been caught by this myself. I built a triple garage a few years back under a building note. I had the roof trusses pre made and the roofing company also did the structural calculations for the wooden lintels and frame. However, The building inspector wanted the walls clad in OSB/plywood and then the membrane for improved rigidity. I didn’t think anything of it at the time but now I see it’s not an ideal solution. The frame was left open inside the garage so it could be insulated and lined in the future....will have to think about this if I ever get round to it!

 

[cookiemonster]

Funnily enough I vaguely remember also buying A1 Protect from Screwfix on the assumption it is breathable, and then wrapping my whole shed/workshop in it. But that was 10+ years ago and the shed is still standing. Perhaps this is because I put a fairly substantial ventilation hole in the back wall?

 

[DBT85]

Steve I can't imagine how you're feeling about it all right now but clearly you have the skills required to set this right.

Even at this time of year (though maybe not with Ceira and Dennis) you can get work donetto start in the direction of putting right the issues you have. It would be a shame to see the rest of the build end up in a pile of splinters rather than taking the time a some money to sort it out.

You can do it, focus on what needs doing that you can do without spending anything right now but still improve the situation and start on the path to getting it all sorted in the coming months.