Thread: shed Upgrades wood heater & bitumen black

The slope of your roof looks a bit "tame" to me, I wonder if that is a contributing factor?

Here's a photo of my roof at 22 degrees pitch.

Looks like very similar construction Wood Borer but yer very different roof profiles. I wouldn't have a clue if the differing roof profiles could contribute to the problem.
- no frost last night, no drips......

Quick update, we had a very heavy frost last night which was actually a good thing in conjunction with the newly applied paint on tar black because it showed clearly just where the drips were coming from & you guys were correct, it appears that the worst of the drips are coming from the areas where the skylights are.
The big question then is what can be done about it? I have no internal lighting at this stage - on the important things to do list - & so naturally i have my tablesaw & my main assembly bench directly under skylights.....
I'd really rather not remove the skylights but then i really do want to be done with these drips. 1 thought i had was to lift the skylights & wrap the steel rafters under them with some form of insulation, not sure if that would help tho....

Originally Posted by Rattrap

Quick update, we had a very heavy frost last night which was actually a good thing in conjunction with the newly applied paint on tar black because it showed clearly just where the drips were coming from & you guys were correct, it appears that the worst of the drips are coming from the areas where the skylights are.
The big question then is what can be done about it? I have no internal lighting at this stage - on the important things to do list - & so naturally i have my tablesaw & my main assembly bench directly under skylights.....
I'd really rather not remove the skylights but then i really do want to be done with these drips. 1 thought i had was to lift the skylights & wrap the steel rafters under them with some form of insulation, not sure if that would help tho....

Rattrap I live up the road a bit from you at Port Sorell. I probably don't get quite as many or as intense frosts as you however our sheds appear to be very similar but I don't have any problems with condensation. The most obvious difference in our sheds appears to be the pitch of the roof. Perhaps the lower pitch of your roof is not allowing the condensation to drain away.

A pic of my shed's roof is attached.

You could well be right Hitch. wood borer suggested the same. Tho its not like theres a lot i can do about that issue.... I'm now thinking its more connected to my skylights as that's where the majority of the drips were this morning. Although you have skylights Hitch & no drips. hmmm. Your skylight sheets are a polycarbonate by the look of them where as mine are the older fiberglass sheeting. They're not clear like yours but do let it some light. I wonder if that can play a part?

fibreglass does condensate more than poly but the issue is the skylights have to go your options for light are electrician obviously, make some windows yourself using the tools in your shed or go with the aluminium variety and a third one that is little used is to put skylights in the walls. for security reasons you only need to go above the last wall purlin ,and you can reuse the roof skylights if they are in good nick. replace the roof sheets and insulate. the workshop where i sub contract from has skylight in the walls and they let heaps of light in

bitumining the rafter or even insulating it wont stop the water dripping on the rafters so any more efforts there wont help good luck steve

I think you are right Steve. I think my next move should be to replace the skylights & wire in some lighting. That means its going to have to wait a few months tho. I'll have to look into putting windows in the north facing wall.

Have you ever sat under a pergola with clear or even tinted roofing on a hot day? It is almost unbearable. The same goes in your shed with those silly "skylights". I've been working at a bench with the sun belting through the "skylight" on the back of my neck and I had to move for an hour or so till the sun moved over. I vowed never to have these in any of my sheds again. And windows are asking for trouble from those light fingered bastards that think they need your stuff more than you do. If you really feel need for natural light, then as Steve had suggested, use the skylight material, and add it to the top 12 inches of your walls. You might need some extra wall purlins to make it work.

Thanks Yonnee, yer i tend to agree with you on the subject of clear sheets. The semi clear sheets i have now are quite good thru the summer, they throw down heaps of natural light without all that heat. On a cloudy day they're not of much use tho, thats when the indoor lighting is needed badly.

I have a corrugated colourbond roof laid over foil backed insulation and supported by 200mm purlins. Because I live in the tropics, the shed traps cool air during the night and at sunup the roof has condensation forming on top with enough forming to fill half a bucket (9m x 4.8m roof).

I've only seen this phenomenon on insulated roofs, uninsulated has no condense as there's no cool/warm differential, in your case warm shed, cool outside air and in my case warm outside air, cool shed. All I can suggest is another layer of insulation around the purlins as they are a thermal leak to the outside air via the squashed insulation and must be at a lower temperature. you could experiment with taping some insulation round a section of purlin.

Hope this helps.

I haven't gone any further with fixing this problem just yet tho i was speaking to a guy at the local hardware store that only works there once a month & he has seen the exact problem & found the best fix for it is a second sheet of laser light over the existing sheets but with a narrow spacer to create a small air gap.
He says that this way the frost can't fall on the bottom skylight sheet, if it can fall on it, it can't freeze any moisture in the air onto the steel rafters.
He also said that the lower the pitch of the roof the worse the problem can get which fits in very nicely with exactly what has been said in this thread.
As you can imagine i'm very keen to get this fixed but i've got a couple of projects on at the moment that are sucking up all my limited attention so for now this problem has been pushed to the back of my mind. Stay tuned tho as i plan to try this method over 1 skylight in the next few weeks.

Graz, it sounds like the problem is completely reversed in the tropics. I did briefly consider adding insulation around the steel rafters however that would also mean lifting the entire roof sheeting - no thanks.
Jacky, the door to the left of the drum heater is a roller door for the car, its always kept closed when not in use. I've pretty much nailed down the cause of the problem, theres a couple of main culprits - skylights & a low pitch roof - tick, tick.
Just as soon as i can get round to ordering a sheet of Laser Light & get a dry weekend i'll give this fix a try, won't take long to get a result we are having heavy frosts pretty much every night now.

I get this problem too on the flat lean to roof at the rear of my shed, the main shed roof (22° gable) doesn't drip. My new shed has Permastop insulation I havent seen any drips yet.

I had to do a search to see what permastop insulation was, looks like good stuff - foil sisilation with a pink batt layer. Wouldn't help my issue however as its only under the skylights that the condensation occurs, elsewhere the standard sisilation does the job fine.

Hello Rattrap, not sure how / if this helps, last week I was at a training seminar ( I'm a NSW builder ) one of the speakers was spruiking a product that was widely used in the USofA and NZ to combat " sick home syndrome ", it had an extremly R value but also doubled as a moisture barrier.

You will get condenstion whenever the temp' differential is 8 degree ( or more ) the moisture on your battens - or any section is coming from within the building, not as falling frost, I'm guessing the best longterm fix would be to lft the roof sheets ( as has been suggested ) and to increase the insulation, I think if you paint the steel with bitumen or anything you will still have the problem, another suggestion would be to do what the poms do and run a de-humidfyer ( sp???), if the skylights in the roof are a problem, is it possible to change them to North facing wall ones??.

Good luck with it, there is nothing worse than rusting tools.