Shed roof pitch too shallow, need advice to stay with pitch

happyhero

Hi everybody I need some advice and guidance, I’ve mucked up a few years back and now I am sort of having to resolve the problem I’ve created. I either must have done the job well first time or more likely the materials I used saved me for this long, what I am talking about is the shallow pitched roof on my timber cabin which I use as a workshop for carpentry.

I bought this cabin 2nd hand in 1995 and had some timber cut to the same profile so that I could make it nearly a meter deeper and wider. The original roof had felt tiles and was in poor condition so I made a new roof for it and had some tiles shipped from Holland at the time (My dad lived over there and could manage to do it cheap back then with an arrangement with the lorry company). I also bought some weird roof covering from Holland, meant for shallow pitched roofs, to be laid on top of the timber roof.

Incidentally the roof is steeper on one side than the other, as one side is much bigger than the other, it’s not an equal split roof over the cabin.

I’m a lot better at stuff now than I was then but I think I missed something back then. Ok the Cabin needed a new roof which I could make but when I made the building wider it effectively made the roof pitch even shallower. I also changed the covering (not sure if the felt tiles would have coped better). Anyway it has lasted more than 20 years with the roof timber (xxxxxmm tongue and grove) before it started to rot in the last year or so in odd patches. The timber has rotted through to the inside in patches creating a soggy bit of wood I can poke my fingers through in the worst places.

The pitch of this roof has ended up at 7degrees and due to the way the tiles lay they are only 1 plus degrees pitch so almost nothing, thank god it ended up at least a step in the right direction rather than backing up on itself.

So I need to replace the timber and see what is going on above to cause the problem.

I have started removing the tiles and so far have found no clumps of debris that I expected. I thought leaves and stuff had blown under and got wet and stayed wet rotting the roof but there is nothing to see yet like this.

Soon I will strip the rotten battens and then the funny plastic ventilated covering. Anybody seen this before? Is it any good?

Anyway I have looked at changing the pitch, or trimming it to be steeper, and it would cause all sorts of problems so I feel I am stuck with the pitch, and I really want to use the same tiles I have just taken off the roof so other than treating it like a flat roof I am looking at what else I can do. My thinking is I could renew the timber and paint it with some sort of black tar like stuff that would seal the timber if I fitted nails or screws into it. I would be tempted to paint the battens with it too to preserve them and create a better seal onto the timber roof.

Is this feasible, is there a substance available to do this?

It lasted over 20 years the first time so I think this method could last longer, if the products are available and reliable.

The whole cabin is virtually under a mass of branches so don’t know if that helped but after seeing the terrible pitch of the tiles I was amazed it’s taken this long to damage the roof timber.

System

You can get metal sheet with markings like those tiles, tbh I'm amazed it's lasted that long!
You'll not find much which is recommended for a pitch of roof like that that isn't sheet/membrane - anything else is asking for trouble, painting timber with bitumen sounds like a bad idea, it'll just mean the timber holds any moisture in it, proper treated timber would be advisable and use a modern membrane suited to your finish (tyvek or so)

getmore4less

single piece of rubber sheet once the structure is sorted.

EPDM is the google word you need.

happyhero

getmore4less wrote: »

single piece of rubber sheet once the structure is sorted.

EPDM is the google word you need.

I love the look of this stuff and how it works but what about my tiles and fixing the battens, can they still be fitted, ie they would perforate the rubber skin?

getmore4less

I was suggesting you ditch the tiles completely.

if you want the shingles/tiles look then that is a different solution.

maybe standard roof lining is the way to go