Leak where garage roof joins flat roof

spwlsl · 21 Feb 2010

Before we bought the house (10 years ago), an extension was built behind the garage and joined to the house (there was a gap between the garage and house about a meter wide).

The extension has a flat roof and so the garage roof drops below the flat roof - hopefully this shows what it looks like :

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spwlsl
21 Feb 2010
1

There is a leak where the flat roof meets the garage roof.

These pictures show this from the inside.

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spwlsl
21 Feb 2010
1

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spwlsl
21 Feb 2010
1

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spwlsl
21 Feb 2010
1

The garage roof has a wooden board under the tiles and as the pictures show a it is wet along some of the board (it is not wet across it's whole length) so there is clearly a leak.

These pictures show the outside of the roof :

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spwlsl
21 Feb 2010
1

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spwlsl
21 Feb 2010
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spwlsl
21 Feb 2010
1

I'm not really quite sure where to start in looking at where the leak might be - any thoughts ?

Thanks

Steve

noseall · 21 Feb 2010

Does the leak happen to coincide where those two tiles were recently put back into position?

Is that chipboard i can see?

spwlsl · 21 Feb 2010

I don't know when those tiles were moved - I didn't do it and as far as I know no one else has been up on the roof.

It certainly looks like chipboard to me.

ladylola · 21 Feb 2010

It looks to me as if the covering has failed and something like flashband has been put in in an effort to resolve the problem i.e. photo 6 because looking at the first 3 photos it seems water is getting in where the flat meets the slope.
I'm afraid the only option is to remove and replace boards and refelt

spwlsl · 21 Feb 2010

Yes - the flashband was my (clearly poor) attempt at sorting this.

When you say "remove and replace boards and refelt" - is that the whole flat roof ?

ladylola · 21 Feb 2010

To be honest if the roof is chipboard then yes I would replace it all as a matter of course. The rafters don't seem to be that bad, they would only need replacing if they are badly decayed. Treating them would give piece of mind but once the source of wetness has been removed that will effectively cure any wet rot that is there. Replace the chipboard with either exterior ply or softwood boards.
Also I would replace all the felt too. It's all the same age so it's likely to fail again and you wont get a good result trying to bond new to old.

noseall · 22 Feb 2010

There also appears to be a cracked tile seven courses up and about seven tiles across to the left of the left hand shifted tile.

Looks split down the middle.

ladylola · 22 Feb 2010

noseall said:
There also appears to be a cracked tile seven courses up and about seven tiles across to the left of the left hand shifted tile.

Looks split down the middle.

Specsavers don't make much money out of you do they!

spwlsl · 23 Feb 2010

That's really well spotted ! I'll go up and have another more careful look to see if there are any more.

Could a split like that cause a lot of leakage ?

If I look from the inside would I be able to see evidence if there was a leak there ?

Thanks

Steve

noseall · 23 Feb 2010

spwlsl said:
Could a split like that cause a lot of leakage ?

Hard to say, but i would replace any split or slipped tiles then eliminate them from your enquiries so to speak.

Not knowing exactly how long the damage has had time to act does not help. In some instances, problems like yours occur the second a builder carries out alterations that are subsequently bodged, thus having plenty of time to manifest themselves.

Cowboy alterations.

These jobs really require a site visit to ascertain the fault though we will do all we can.

spwlsl · 23 Feb 2010

Thanks - all advice is much appreciated.

Is replacing a single tile something an amateur can do ?

Alastairreid · 23 Feb 2010

simple enough,

* To replace a single broken roof tile slide up the tiles onto your broken tile. Alternatively, in the course above the broken tile use wedges to lift the tiles either side of it.

If a tile is nailed to a batten, use a slate ripper to cut through the nails. simply levering the tile up should release it.

Slide the new tile up into place. It is not necessary to nail or clip it in place.
Reposition any tiles you moved and remove any wedges.

noseall · 24 Feb 2010

alastairreid said:
simple enough,

* To replace a single broken roof tile slide up the tiles onto your broken tile. Alternatively, in the course above the broken tile use wedges to lift the tiles either side of it.

If a tile is nailed to a batten, use a slate ripper to cut through the nails. simply levering the tile up should release it.

Slide the new tile up into place. It is not necessary to nail or clip it in place.
Reposition any tiles you moved and remove any wedges.

You forgot the...."then have a nice strong cup of tea".

noseall · 24 Feb 2010

alastairreid said:
If a tile is nailed to a batten, use a slate ripper to cut through the nails.

I doubt any of those are nailed there doesn't seem to be enough evidence of the laths splitting.

I also like the eaves course, the roofers have simply pushed the bottom tile up and is not sitting on a lathe/batten!

The roof is a bodge through and through.

The more i look at it though the more i am convinced it is the flattie that is at fault though judging by the workmanship i can not be sure.

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Leak where garage roof joins flat roof

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