Replaced shed roof and leaking help and advice needed please

[davies5390]

hey guys

im generally a handy DIY'er so to speek and will give most things a go

on the weekend i had to replace my shed roof, size 3.6mx3.0m
the whole roof was shot so i completly redone it all

this is what i did i repalced all the 6x2 joists 600mm apart used 9mm OSB board (8x4) ontop then used roll felt over the top of the osb boards with a 50mm over hang on each strip allowing a nice run off.

the roof itself is on a slope of about 10/15 degrees

now its rained all weekend and on the joists where the osb boards have joined there are drips of water coming through into the shed not a massive amount but around 4 dripps on 2 seperate joists and its concerning me. The osb boards are dry underneath so i dont think its the felt.

any advice on how i can fix this? another layer of felt on to[p maybe? have i missed something important for a basic waterproof shed?

help needed as soon as poss as weather not good through winter and do not want all my hard work and new wood to get ruined,.

thanks

 

[joe-90]

Did you nail it? 9mm is a bit stingey.

 

[davies5390]

i screwed the osb board to the joists and used 20mm felt nails for the felt

im gutted its leaking as dont want to take it all of and start again. i was advised that if i was not going to be hanging anything from the ceiling or walking on the roof at all then 9mm would be fine for a few years

 

[joe-90]

The likelihood is that the construction being flimsy it bounced when you hammered home your clouts. I suspect that is where the leaks are coming from. Go round them with some kind of sealant.

 

[davies5390]

how do you mean sealent? should i remove the felt and seal all the joints and then relay the felt ?

just refelt over the existing felt?

im struggling to find where the water is getting in as the whole roof is coverd and felted.

 

[cotswoldbuilders]

Its best to avoid using any tacks, try a heavy duty green mineral felt.
I would use a torch on felt but this is probably beyond your means so either stick it down with cold adhesive using a notched trowel, ( keep the adhesive warm before using, easier to apply ) or failing that fix it down with some roofing battens going up the roof and try to get the nails/screws to hit the joists.

Give the felt more lap, 50mm is not really enough.

 

[catlad]

You would have been better to ask for a bit of advice before rather than after. If you are not going to seal the the laps, then at that pitch I would say you need to have 150mm overlap. Rubberoid do a lap mastic.