Workshop roof problem

[user 466]

Apologies in advance for the long post. My garage, that I use as a workshop, is approx 22 foot square. Its a nice space although I have to maintain the illusion that one day we will be able to park cars inside it.

The problem is that it has a galvanised steel corrugated roof and, in Winter, condensation problems result in it 'raining' on the inside. I have put up with this already for several years but now that I have become more serious about woodworking and have invested in some stationary tools, it is a real pain.

Basically from about this time through to Spring, the combination of a constantly dripping roof and the cold means that every bit of equipment has to be covered and I cannot do any more work.

Have any of you had a similar experience and how did you solve it?

I am told that the answer is to insulate the roof space. The roof is supported by frames (about 9" high) made of steel angle, welded together from mountings buit into the garage walls (brick). The outside roof profile is a typical shallow V shape. The bottom of the roof supporting frame is parallel to the roof at the edges and flat for approx 4ft under the ridge.

I had intended to use 3 x 2 cls studwork timber bolted through the 3" wide edge up into the bottom of the steel frames (supports) at 2 foot centres. Then use cross pieces on 4 ft centres (staggered) and buy waterproof(?) green chipboard flooring panels from Wickes (8ft x 2ft) to form a suspended roof / ceiling. Above this I guess I would need some form of insulation material but, again, I'm not sure what type to buy.

Does this appear to be a reasonable way forward or am I missing something?

The other concern I have is that, occasionally, we get a mouse in the garage. Would I be building a huge nesting site?

Your views would be very welcome. Thanks.

 

[StevieB]

Hi SMD,

OK, if I read your post correctly, then the condensation is simply a result of warmer air in the garage condensing on the roof then dripping back into the garage. To stop this as you say you would need to stop the warm air getting to the roof. Simplest way I can think of to do this is as you say insulate the ceiling. Either with rockwoll type insulation or possibly polystyrene sheets. I would probably put a damp proof membrane between the insulation and the roofing sheets so that any condensation that still formed did not sit in your insulation and make it waterlogged. This will mean any condensation that does form will run along the DPM to the lowest point, so you may want to engineer a lowest point to prevent water sitting in a puddle on your membrane. However, if the insulation is thick enough I would have thought condensation would be minimal.

As for the mouse, stick a piece of Mars bar on a mouse trap - they go nuts for it. :twisted: If you want to be kind, put a piece in a humane trap, then once caught drive a couple of miles away and release it. :wink:

Steve.

 

[ike]

I'd just add to Steves advice that chipboard'll add a very significant load to the roof framing. If you use a hogh performance insulation (polystyrene, or that foil faced foam board stuff they use in cavity walls etc) you could probably get away with panelling using something like 1/4" oil-tempered hardboard which is also water resistant, and will save weight. Might need battens a bit closer though - say 18" or so.

cheers

Ike

 

[OLD]

Just found this on google:-http://www.foam-insulation.co.uk/just have the insulation sprayed job done no more condensation.

 

[Dewy]

SMD I have a similar problem with mine.
The garage came with a corrugated concrete type roof (similar to the old asbestos sheets and I changed one and a half sheets for clear PVC to allow more light in.
Thae bulk of the roof does not suffer with condensation but the PVC panels have a constant drip from them where they touch the steel roof joists.
I have to cover everything with polythene sheets in the winter to keep the water off.
I've had enough and will be replacing the PVC with the spare roof sheets to stop this problem.
I'll just have to install better lighting to compensate.

 

[devonwoody]

As for the mouse, stick a piece of Mars bar on a mouse trap - they go nuts for it. If you want to be kind, put a piece in a humane trap, then once caught drive a couple of miles away and release it.



I was returning from our municiple tip back in the summer and when I had to stop at the trafic lights a lovely sight greeted me. A field mouse appeared on the top of my dashboard.
Minnie was obviously interested with her cruise :lol:

These field mice creep into my garden refuse sacks, so I suppose she lost her family on that trip to the tip.

Took some persuading to vacate the car when I got back home, but did manage to catch the lady and present minnie to the wife showing my prowess at pulling the ladies.

 

[user 466]

Many thanks for the advice.

I like the idea of using a damp proof membrane (thanks StevieB). Not having done much in the way of building, I haven't come across this stuff. Is it readily available from the likes of B&Q, Wickes type outlets or would I need to go to a builders supply place?

Ike, thanks for the suggestion re 1/4" oil tempered ply. I'll explore this one further and cost out extra framing versus, hopefully, cheaper sheeting material. I don't think that the weight of chipboard would give me a problem since the steel supporting frames are very substantial (they are certainly a real pain to drill through!) - 2 1/2" x 2 1/2" x 1/4" L shaped angle with many cross bracing pieces.

I think that I may have mislead people re the mouse problem!

I don't have any mice in the garage at the moment (that I'm aware of!), but have, in the past, found the occasional abandoned nest at the back of a drawer that I don't go into too often. If they do venture into the garage then they don't usually stay long. I have never bothered to use traps or anything else.

Since the roof is corrugated steel, there are gaps between the roof sheet and the walls. Some of these are filled with cement, some are open.

My concern is that, if I use something like Rockwool insulation above the chipboard or hardboard then mice may find this a very attractive place to nest and I may have a more substantial problem than now.

I am unsure how best to seal these gaps between the roof sheets and the walls. I know that some kind of shaped foam infill is available but I have not found any for the profile of my roof. (it's sort of rectangular corrugations not round ones).

Your comments have reassured me that insulating the roof is the way to go. It's a nightmare not being able to leave any tools out and cast iron is a definite no no with the current conditions.

I bought a bandsaw about 6 months ago and, since it has a cast iron table, it is still in the box until I can sort this problem out.

Thanks again.

 

[Rattie]

I am unsure how best to seal these gaps between the roof sheets and the walls. I know that some kind of shaped foam infill is available but I have not found any for the profile of my roof. (it's sort of rectangular corrugations not round ones).

If you don't find any purpose made foam filling strips, it sounds like an excuse to use expending polyurethane foam. If you make pigs ear of it, then you can always attach some simple soffiting to cover over once the foam has filled the gaps.

Bear in mind that the foam needs damp surfaces to work - probably not a problem in your case :wink:

Martyn

 

[OLD]

Eaves filler just got a load for big 6 sheets from http://www.slecladding.co.uk/?source=svsvery good and helpful check out site and give them a ringhttp://www.slecladding.co.uk/foam.htm

 

[StevieB]

Yup, damp proof membrane can come from the usual places such as Wickes or BandQ, or a builders merchants. I lined my workshop with some from the builder centre down the road.

DOnt have a problem with mice and insulation, but the birds love pinching it from our loft and spreading it round the garden (old house, no proper eaves, long story). In the end I put up a fine wire mesh over the outside of the rafter ends to stop them getting in. Mice are a little smaller though so as suggested expanding foam would be a good way to go. It does break down in sunlight though, so it will need covering itself.

Steve.

 

[CYC]

I don't know if it's the same in the UK but here going to B&Q to get any building supplies will cost you a lot more than your local builders provider!

But then again this IS rip off Ireland I am talking about