leaky garage roof

[sawman]

We have a great garage, its about 22' x 20', with no awkward pillars, but it has a tendency to leak. I need to get it sorted, but how much of a project is it?

it has a shallow pitch to the roof ( 16degrees according to the inclinometer on my iphone) and its cpvered in what seems to be asphalt shingles. Its about 10 years old - heres some pics:




Here's some damp beams



internal roof construction


More damp beams


some of the wooden beams appear damper than the others, I guess at least some will need replacing, I wonder if they are man enough for the job (4"x2"). What is the most likely reason for the room to be leaking? poorly applied shingles? or degradation of the material? . Any tips or guidance gratefully received.

thanks in advance

[Eddieslofart]

Is there evidence of leaks when raining ? Are those damp patches on the brick ?

They look to thick to be shingles, especially with a cemented verge.

Dekra or Metrotile sheet would be the easiest fix.

[sawman]

yes, when it rains reasonably hard its drips inside, and the usually about 2 feet in from the wall, in the second pic you can see staining of the black roof lining that appears damp sometimes.

We did have an earlier issue, where the gutters were not properly supported and so holding water and overspilling onto the wall. The walls appear not to be damp, but its fair to say the garage is damper than I would like - I have the doors open when ever I am in the house and its not raining

[Wayne E Edge]

Judging by the verge and the amount of courses I'd say you had Ashmores on there. Pitch is too flat.

[sawman]

finally managed to get someone to quote me for mending the roof. He came recommended and is suggesting using marley mendip interlocking tiles, which looking at the marley spec sheet seem to fit the parameters.

quote just shy of 3k for re-tiling, new laths and breathable felt, inc scaffolding - does this sound reasonable? - oop north..

[Eddieslofart]

3k i would expect to pay darn sarf, bit strong considering how easy a roof it is.

New breather membrane ?

[sawman]

yes, breather membrane, also dry ridge and verges

written quote 2.8K

[TA14]

What size timbers are those? Are you sure that they won't sag under the increased load?

[sawman]

4x2 , some are less than healthy so will need replacing, its certainly a question i had wondered about.

[TA14]

Try 6 x 1.5" screwed to the sides with noggins at half span.

Who designed the steel beam? You want to check the strength of that. If it had shear connectors into the blocks above it would be great; back to reality, if it needs strengthening you're looking at a plate below or some strapping arrangement to connect the blocks to the beam.

[sawman]

TA14 said:

Try 6 x 1.5" screwed to the sides with noggins at half span.

Who designed the steel beam? You want to check the strength of that. If it had shear connectors into the blocks above it would be great; back to reality, if it needs strengthening you're looking at a plate below or some strapping arrangement to connect the blocks to the beam.

I am a bit concerned about making the roof heavier than it is, as ther is a little sag in the timbers already.

do you mean 6' timbers screwed to existing ones? would it be an idea to put another longitudinal beam halfway between the roof apex and eaves to support the existing timbers?

How about a non tiled roof? I know felt would look more sheddy than garage, but I guess it would be lighter and potentially sealable?

[Eddieslofart]

Eddieslofart said:

Dekra or Metrotile sheet would be the easiest fix.

As previously.

[sawman]

Eddieslofart said:

As previously.

Thanks Eddie, just checked that out, and found a local contractor who uses this stuff - will see if I can get a quote