Leaking Flat Roof

phiso

Hi

We have a flat roof over the garage and utility room that meets the gable-end wall of our 70's semi.

We have suffered from leaks for years, predominantly at the point in the utility room where the flat roof joins the outside wall of the house proper. After spending hours over the years applying roof sealant, we decided to have a new flat roof fitted as it was showing a lot of wear.

Problem is, it still leaks in the same spot!

In fairness to the roofer, when I called him he was out in about an hour....on a Sunday...in the pouring rain! Great service! He said that he couldn't see any poor seams (I went up with him & it seems true) and he thinks that the water is getting through the outside wall through the mortar (which I would agree is badly cracked in places). He is going to come back when the roof is drier & pour water over sections of it to make sure it isn't leaking and will re-point if we wish for £250 once confirmed that this is the likely cause of water ingress.

So, my questions:
1: Is pointing it a possible cause of the leak? If rain is getting through the mortar, why doesn't it just run straight down the inside of the cavity?

2: I noticed that he did not replace the tin flashing from the old roof but instead he lapped felt up 2 courses of bricks before putting that into the mortar. I haven't seen this done before although I have noticed it on a few other houses in our area since.

Any advice gratefully received!

Phil

BargainGalore

Pointing is a possible cause as is old brick over time

NualaBuala

Hi, we have the same problem - mind if I ask how much it cost to get the roof redone? I think I'll have to get it done but have no idea how much it'll cost.

phiso

Hi NualaBuala

We had ours done for £850 which included the flat roof over the porch and front widow & the workmen were great - so tidy. Old roof stripped back to the wood and rubbish all cleared.

We had a quote for £4500 (gulp!) for the new rubber-type roof and £2500 for felt so shop about! The roofer was recommended by the chap who replaced our fascias and he came back to ensure we were happy with the work the roofer had done.

Phil

NualaBuala

Thanks Phiso, great to have a ballpark figure. I'll start asking around to see if anyone knows a decent roofer in the area.

Swipe

Flat roofs are notoriously difficult when diagnosing the source of water ingress. I'm currently troubleshooting my sun lounge roof, it's almost always only possible through process of elimination and the end result is usually from the last place you would have imagined.

chivers1977

My flat roof was £600 which included new insulation, new wood and rubbish clearance in Kent for a council "Fair Trader". I believe that mine is 13" by 20". No leaks since!

ormus

a local chap did mine for 250 quid. completely covered the roof in bitumen.
its been ok for about 3 yrs now.
we also had him back to repair a downpipe box in the front valley. cost was 120 quid.

similar to photo below.

NualaBuala

Thanks guys, those prices are good - I really was afraid it'd cost thousands. At least I won't be afraid to get people in to quote me now.

bellajack

Original query from phiso re leaks;
Almost certainly it's the flashing. Insufficient height above the flat roof and insufficient insertion into the brickwork with poor pointing at this point.

phiso

Thanks bellajack. Perhaps I was a bit inaccurate with the height, it's actually higher than the previous flashing and (to my my non-builder eyes) well into the wall and looks sealed on top as well.

I think I'm going to have to cross my fingers & go with the pointing if the roof appears not to leak under testing.

The leak only seems to happen when the wind blows the rain hard against the gable end (like today) - we tend not to see the leak when it's not driving rain.

Phil