can't understand why my shed roof is leaking....

[r896neo]

I honestly don't know, sorry. Perhaps someone else can chime in.

 

[Burnerman]

Please, I'm not trying to be a smart ass or knowledgeable, but I'm imagining that roof with 3' of snow sitting there for weeks on end, like it can do here......
Are the vertical supporting posts sufficient in dimension and number, especially towards the back?
John

 

[sadexpunk]

please dont apologise mate, im not offended, i had the same thoughts myself once built. bit late then eh?

all i can say is i hope they are! do you mind me asking why you ask 'especially at the back'? does the back take more strain?

im always thinking about what i could do to improve this, the latest thought was a couple of wooden supporting wooden poles maybe, placed between decking and roof joists at relevant places just in the winter. you know..... "summers over now, we wont sit in it again this year, bring the emergency winter struts out now". soon as it wont snow again take em out and its ready for summer again. dunno if it needs them or not, but if i can minimise the gamble i will.

still wouldnt mind advice on the best bitumen product for a good seal if you dont mind?

thanks a lot

 

[Burnerman]

I must say, it looks a grand piece of joinery from here!
The wall at the back, with the horizontal boards......how is the roof secured to that? I thought maybe a couple of verticals there could help with the heavy load, and perhaps another on the left side.
Anyway, that's not based on any experience at all so maybe others will chip in.
I've noticed a car port near to me fixed with a one piece rubber roof - a superb job from what I can see - and if I was in this situation I'd certainly go for that.
Anyway - if I have a flat roof that needs sealing, I head for a brushing product called Evercryl (MKM ) which is a solvent based viscous liquid reinforced with glass fibre.
Regards
John

 

[sadexpunk]

thanks mate. the shell is constructed by sticking 8 x 4" square posts in some uneven ground, then screwing 4x2 all the way round it at top and bottom for roof and floor ring beams. then joists and noggins are screwed to the ring beams. hence another fear of mine that a weighty roof would have the weight actually on 'just some wood screwed to the posts' rather than down through the posts. all things ive thought about and learnt since knocking it up.
i looked into the one piece rubber (EPDM or summats) but too pricey as my budget has been blown by all the timber. didnt think id have trouble with a felt roof but if i spend much more on it, itll get to the point where i may as well have gone for the rubber :-/

thanks, ill look into that evercryl.

cheers

 

[sadexpunk]

looked into the evercryl and found its exactly what i used over my joins and hasnt worked. i do realise tho that i should have gone under the overlap tho, not just pasted it over the top hoping for a seal.
im about to start re-felting today with more rolls, more bitumen adhesive, and wondered whether its a good idea to either lay a tarp or DPC membranne underneath the felt as a belts and braces approach. is this a decent idea?

thanks

 

[r896neo]

As I said before, for me, bitumen adhesives etc are only for glueing felt laps down to prevent wind lift. They should never be relied upon as waterproofing for me.

Keep it simple and use the felt and your fall to waterproof.

Putting any kind of dpm under there is a bad idea in my book. Just an extra layer to trap moisture and perhaps condensation.

 

[sadexpunk]

Keep it simple and use the felt and your fall to waterproof.

not entirely sure what you mean. i didnt get a reply for a couple of days so guessed at what to do. ive put more felt on with bigger overlaps now, and a fair old bit of adhesive. dont really understand what you mean by using the felt and my fall to waterproof? by fall do you mean the pitch? we've already concluded that my pitch is less than optimal so cant be relied on to waterproof.

Putting any kind of dpm under there is a bad idea in my book. Just an extra layer to trap moisture and perhaps condensation.

oops, as mentioned, i had to crack on with it, hadnt got an answer on here so just went and laid one, hoping that itd be a belt and braces approach. as for the condensation, im hoping that as its all mostly open, i wont have toooo many problems with that.

thanks a lot

 

[bigbird76]

I was gonna say why dont you fit some bitumen corrugated sheets on top of the felt, sheets have about 15yr life I use onduline ones, About £13 each in wickes

 

[bigbird76]

I built this a few weeks ago it has breathable membrane on the roof followed by shed felt followed by onduline bitumen corrugated sheets, The smaller frame is my log storage work in progress using wood etc that i have left and that is going on the left side of my summer shed veranda hybrid thingy.

P.s i did the same on a lower 10x6ft shed and its been bone dry, This one though is 3x6m but shed is 3x3m the decking is just somewhere to sit in the shade or cuppa tea if we get the odd shower.

Leigh

 

[sadexpunk]

thats lovely mate, nice one.

i looked at the onduline sheets, even bought them ready to put on, then thought better of it as we live on a ridge where the wind gets up quite badly sometimes. its not uncommon for shed roofs to go for a wander from time to time and i looked at how id built mine and realised the sheets would have to sit on top of everything, with a gap that probably wouldnt stand a chance if the wind got under it. also not sure if i wouldnt get 'capillary action' on the onduline overlaps too cos of the shallow pitch. if it does it with my felt, why wouldnt it with the sheets......

if this version of the roof leaks tho, im going to have to look at something else, as the felt just wont work. maybe strip it all down and do EPDM or something. cant really afford to chuck more money at it tho.

thanks

 

[jackieboy]

I've seen condensation cause some problems to.

New under felt, new cap sheet. don't use clouts use a lot of felt adhesive .

 

[Mursal]

Dont fully rule out undulating (corrugated) sheeting, if unsure use screws with a sealing washer, but nails will be fine.
Drill the sheet first

 

[sadexpunk]

I've seen condensation cause some problems to.

New under felt, new cap sheet. don't use clouts use a lot of felt adhesive .

ive not used under felt, ive used a damp proof membrane, but not sure its going to be very effective, just hoping ive actually cured the leak so the membrane wont be needed. ive used new felt, no clouts on top, and lots of adhesive. funnily enough the added felt adhesive seems to have soaked the felt and made the edges a bit wavy, in a bit of a 'corrugated' effect. ive splodged lots of adhesive in where the undulations are highest, but it doesnt look as neat as mk1 (which leaked). just waiting for rain now, see how it goes. ive thought about weighting the edges down with planks and bricks for a day or so to force the edges flat, but dont know whether this will actually break whatever seal is there now. probably better to leave alone and see how it deals with rain first. if it ISNT broke, then dont fix it

Dont fully rule out undulating (corrugated) sheeting, if unsure use screws with a sealing washer, but nails will be fine.
Drill the sheet first

ill consider anything really, corrugated sheets would be acceptable, but as i mentioned before, i live in a windy area and i cant see how these sheets would stay on if some of our winds got underneath them.

thanks chaps

 

[r896neo]

Waves in the felt sounds like very bad news. It may be worth try to clamp it down. You don't want to crack the felt though if its not pliable enough. Warm it up a little perhaps?

If your area is very exposed wind uplift will possibly tear the whole roof off so make sure its well secured to the posts.