Shared Flat Roof - Temporary Repair

[wytco0]

A garden hose and wet the roof as much as you can should tell you something. Do the flat roof area first.

masona, unfortunately the whole roof is flay

 

[wytco0]

OK more progress, the parapet walls and cap stones have been repaired and rebuilt where necessary.

I am now thinking of biting the bullet and going for a coat of Flexacrly over the whole roof, It will cost about £500 but if it saves the roof for a couple more years it will be worth it.

I have started removing the granite chips along with the mud, moss and lichen etc that on the roof. I have been using water to try and wash it as clean as I can. Is there something that I can buy that helps remove this sort of thing?

Also I have noticed that there is a split in one bit of the lead flashing, I have tried to repair this with some of that bitumen backed lead stuff but it does not stick to the lead very well. Does anyone have any idea of how I can repair this?

Lastly !! should the lead flashing be hard against the felt or should it be slightly proud of it? at the moment its slightly proud all round. I am not sure if it should be sealed to the felt (which it is not) or whether it should stand above it and act as a drip deflector?

Sorry for the silly questions

 

[masona]

I have started removing the granite chips along with the mud, moss and lichen etc that on the roof. I have been using water to try and wash it as clean as I can. Is there something that I can buy that helps remove this sort of thing?

A wide broom I think !

Also I have noticed that there is a split in one bit of the lead flashing, I have tried to repair this with some of that bitumen backed lead stuff but it does not stick to the lead very well. Does anyone have any idea of how I can repair this?

See this.

Lastly !! should the lead flashing be hard against the felt or should it be slightly proud of it? at the moment its slightly proud all round. I am not sure if it should be sealed to the felt (which it is not) or whether it should stand above it and act as a drip deflector?

Not normally sealed to the felt. A bit difficult without seeing it. A photo would help a great deal.

 

[wytco0]

Masona,
Thanks for that, I am using a wide broom so it looks as though I am on the right path The bit I meant though was getting rid of any remaining organic living stuff! I thought it might be worth killing any tiny bits I miss.

I will try and take a photo tomorrow but the felt is has a 45 degree fillet from the roof to the parapet wall, i would guess it goes up one brick up but it could be 2, over that there is a lead flashing thats about 4 inches deep and which is built into the parapet wall like a dpc. it overhangs the felt but does not press hard against it.

I had a look at that lead sealant and it looks good, do you know if it will stick lead to lead as well? I could try bonding a bit of flashing onto the wall and then to the exisiting lead, I am not sure what does stick to lead !!

 

[wytco0]

Sorry didnt get a photo today because it was raining, I did get all the gravel and mud of the roof and washed it down as much as I can, got hold of the first 2 cans of Fexacryl so I hope to start on in tomorrow, if its dry.

 

[masona]

Sorry didnt get a photo today because it was raining, I did get all the gravel and mud of the roof and washed it down as much as I can,

Is it still leaking since you repairs the parapet brickwork ?

 

[wytco0]

masona, I cant be sure because it hasnt rained that much, the leaks were not major but they were enough to make some area stain and I could detect wetness with a damp meter. I have found a few bits on the roof where there are cracks but none of them seem to go through the 3 layers in fact they seem only to be in the top layer. Now that I have removed almost all of the gravel and the mud and crap that was with it I think the roof actually looks in pretty good condition considering its 20 years old.

I want to sort out the lead/felt join if it should be a join and repair the minor problems I have seen. There are 2 places where the water pools and as far as I can see they only dry out by evaporation.

I had thought of washing all the gravel but that is a huge job if I do go for the fleaxacryl treatment I dont need any gravel as its stable to sunlight.

 

[wonderdust]

if you use the bitumen backed lead flashing use a heat gun on the bith first to get it nice and soft then it should stick like s**t

 

[wytco0]

OK i managed to get some photos today, i have put them on this page http://www.flying.demon.co.uk/RoofWeb/

I have added some comments and questions.

I had a closer look at the flashing today and it looks as though it was stuck to the felt with some sort of mastic, however the mastic has all dried up and come off, feeling under the flashing it seems a bit damp.

also the corners do not seem very well done.

Any ideas of how I should deal with the flashing and the corners?

Thanks.

PS wondelust, I wondered if that might work, thanks for the tip.

 

[wonderdust]

if you get really hot it will stick like s**t but where gloves because the bitumen leaks out when you press it down....................bloody burns!

 

[masona]

I had a closer look at the flashing today and it looks as though it was stuck to the felt with some sort of mastic, however the mastic has all dried up and come off

Are the roofing felt stuck to the brick wall under the lead flashing ? How high does the felt goes up to under the lead flashing ? The lead flashing should not have any sealant at all underneath because the lead need to expand and I'm guessing it may have pulled the roofing felt out slightly under the lead flashing & the rain maybe getting in the top pointing joint before you repaired it. Was the leak near the wall side ? Where the puddle are, you need to do a hot pour bitumen and build it up level then the puddle will go somewhere else! It really need a new roof as it seems to be up & down all over the place. I wouldn't do any more work on the flat roof area because you may have stopped the leak. Make sure all the pointing is sound where the lead is into the brickwork and you could use roofing sealant over the joint to protect it further.

Any ideas of how I should deal with the flashing and the corners?

Difficult to explain, I see if I can find a link picture.

 

[wytco0]

masona,

The felt goes about 4 inches under the flashing.

The roof pictures make it look more uneven than it is, in two places where the water pools it is only about 2 mm deep but in the other one its about 15mm. All of the houses in our block seem to have this problem, the water runs from the front to the back OK but does not drain in the the drain shared by each pair.

I now have a big problem that I have caused myself! I have removed almost all the gravel, I was planning to paint Flexacryl over the whole roof but this is expensive, I am having doubts about doing it if the roof (despite me thinking its OK) is actually in a bad condition. If I don't Flexacryl it I will have to do something to stop solar problems on the now exposed roof.

I will try and sort the lead flashing so that it fits closer to the felt all round, I am not sure what tools to use for that, any ideas?

Added by EDIT, what sort of roofing sealant did you mean when you said '....and you could use roofing sealant over the joint to protect it further.
' ?

 

[masona]

If the felt is approx' 4" under the lead flashing then that's okay. If you look on any roof you will find that there is no sealant with any lead flashing. I should leave the lead flashing overhanging as it is which is correct. There's no way the rain can enter underneath providing the cement joints is okay. You could use Flexacryl over the lead flashing joint but they are many cheaper products which is suitable such as bitumen paint or roofing mastic etc if you wanted to refund your Flexacryl instead. I wouldn't treat the flat roof yet because it coming to end of life, 15-20 years is average for a flat roof. At this stage I would put more gravel onto it and maybe a hot pour bitumen where the puddle is to make it a bit more level. Spend money as it need it or you could be wasting your money. If you're saying for long term future then a new roof would be a good investment.

 

[wytco0]

OK I think I will have to have a rethink, I am not sure I have time to get a hot pour bitumin to level or how much that would cost, what about the trowelable stuff I have seen? is that any good?

I think I will us the Flexacryl round the edges and anywhere where I can see problems, then cheaper bitumin stuff elsewhere then some gravel or reflective paint for solar protection.

Does that sound OK, this is only meant to try and get a year or two more out of the roof.

 

[masona]

what about the trowelable stuff I have seen? is that any good?

You can do but you may create another puddle somewhere else ! I would leave it and see how you get on.

I think I will us the Flexacryl round the edges and anywhere where I can see problems, then cheaper bitumin stuff elsewhere then some gravel or reflective paint for solar protection.

Yes no problem there but I would wait for the next lot of rain then take it from there.