Metal profile roof sheets dripping

[Paul TT]

Hi I have a shed with a metal profile roof fixed straight on to timber joists with tek screws am worried about this dripping water as weather gets colder what or how can I nsulate this preferably without taking the roof off completely as I wish to store some classic motorcycles anyone done this or have an answer to this one.

 

[Myfordman]

You can use spray on insulation but dont cover the timber rafters as they need to breathe.

 

[AJB Temple]

If the motorcycles are valuable, I would store them in an inflatable bubble inside your shed. This consumes very little power and is very effective at dealing with a consistent environment. As you are in Portsmouth, keeping corrosion at bay is always a challenge.

Also the units condition the battery at the same time as keeping the bubble inflated.

 

[Lard]

It will happen! I have the same although when I built my ‘shed’ I included an inner breather membrane which has ‘dealt’ with the problem of condensation droplets.........up to a point. The condensation collects On the inner side of the profiled roof, gains weight and eventually the larger droplets fall onto the membrane and run down and out. Without wishing to tell you how to suck eggs the problem is that warm, moist air hits the cold roof and so the only solution is to insulate/ventilate. Boarded insulation will help but even that will not eliminate the issue and so the ultimate answer is to spray insulate the inner face. I couldn’t be bothered with that and so I put up with the ODD (ie rare) drop making its way through the membrane joint at the laps and that’s only because I should have increased the pitch when I designed/constructed the roof.
Hope that’s of use to you.
dq

 

[MikeG.]

We have a professional sheet roofer on the forum, but I've forgotten who he is. Hang on for his advice before you make any decisions.

 

[disco_monkey79]

I had spray foam on my old workshop's metal roof. It sorted the problem perfectly, but I had metal joists, and it also made a terrible mess when spraying it on.

 

[Paul TT]

I had spray foam on my old workshop's metal roof. It sorted the problem perfectly, but I had metal joists, and it also made a terrible mess when spraying it on.

Hi spray foam is nasty stinky stuff and would need everything emptied out was wondering what I could fit on the inside to do the same

 

[Steve_Scott]

If you could face replacing the sheets there is a product that has a fleece type material layered to the building side. It basically acts like a sponge and holds onto the water and allows it to evaporate as the day warms up (as long as you have reasonable airflow). I’ve been toying with this solution but feel if the roof is coming off why not just replace with timber and insulation...

 

[philrosenberg]

I would insulate with either kingspan or rockwool then board your ceiling.

There is an important point to note, any air which seeps past your insulation or percolates through your insulation will still generate condensation and this can potentially rot your roof.

To avoid this you should do both of the following

1, leave an air gap between the roof and the insulation connected to the outside world to allow condensation to evaporate and escape.
2, on the INTERIOR of your insulation fix a sheet of damp proof membrane to act as a vapour barrier. This must be sealed at the edges with tape to make it airtight. Or if you use kingspan with the shiny coating, the shiny coating is your vapour barrier. Use the silver tape to seal this at all edges and fix any damage.

So from the top, down, you should have metal roof, air gap, insulation, vapour barrier, boarding.

 

[Paul TT]

I would insulate with either kingspan or rockwool then board your ceiling.

There is an important point to note, any air which seeps past your insulation or percolates through your insulation will still generate condensation and this can potentially rot your roof.

To avoid this you should do both of the following

1, leave an air gap between the roof and the insulation connected to the outside world to allow condensation to evaporate and escape.
2, on the INTERIOR of your insulation fix a sheet of damp proof membrane to act as a vapour barrier. This must be sealed at the edges with tape to make it airtight. Or if you use kingspan with the shiny coating, the shiny coating is your vapour barrier. Use the silver tape to seal this at all edges and fix any damage.

So from the top, down, you should have metal roof, air gap, insulation, vapour barrier, boarding.

Could I foam the gaps above wooden joist with squirts foam them celotex or king spa between the joists and either foam or seal where the boards touch the joists?

 

[Keith 66]

Im just at the point of replacing the workshop roof but it will with be insulated steel roofing sheets, expensive but worth it.