pocster

Edpm at edges

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Posted (edited)

Hey all

 

Getting my cement particle board down which will have edpm on it .

I’m not going to install it ?

 

But what should I do at the edges ? . I presume he can’t just stick the edpm up stone !!!! 

 

Does the installer provide some ‘fillet’ to get over this somehow ??

 

Cheers 

7F4B9DC0-994D-4192-B381-681830B0CCAA.jpeg

Edited by pocster

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Lead flashing needs to be set into the stone work and then dressed down over the EPDM.  There will need to be an upstand where the EPDM meets the wall, so the lead can be dressed down over it.  There are some details here: https://www.fixmyroof.co.uk/install-roof-flashings/ and a video here showing what looks to be an aluminium flashing trim, rather than lead:

 

 

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6 minutes ago, JSHarris said:

Lead flashing needs to be set into the stone work and then dressed down over the EPDM.  There will need to be an upstand where the EPDM meets the wall, so the lead can be dressed down over it.  There are some details here: https://www.fixmyroof.co.uk/install-roof-flashings/ and a video here showing what looks to be an aluminium flashing trim, rather than lead:

 

 

Hey !

 

ok - that all makes sense !

In the video though he has a nice flat wall ; mines ‘natural’ uneven stone . Is it the same principle just more work ? ?

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18 minutes ago, pocster said:

Hey !

 

ok - that all makes sense !

In the video though he has a nice flat wall ; mines ‘natural’ uneven stone . Is it the same principle just more work ? ?

 

In essence, yes.  Ideally the stone wall should have been built with a mortar course 150mm up from the finished roof height, as that makes the job easier.  Cutting a straight slot through a mix of mortar joints and stone will be harder, depends on the stone.  I had to cut a flashing slot in a Cornish granite rubble stone wall years ago, which wasn't a lot of fun, but that's probably at the extreme end, sandstones are often a lot easier to cut.

 

Dressing the lead flashing down over an uneven wall shouldn't be a problem.

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21 minutes ago, JSHarris said:

 

In essence, yes.  Ideally the stone wall should have been built with a mortar course 150mm up from the finished roof height, as that makes the job easier.  Cutting a straight slot through a mix of mortar joints and stone will be harder, depends on the stone.  I had to cut a flashing slot in a Cornish granite rubble stone wall years ago, which wasn't a lot of fun, but that's probably at the extreme end, sandstones are often a lot easier to cut.

 

Dressing the lead flashing down over an uneven wall shouldn't be a problem.

Yeah the wall is random stone ; so no chance of a nice level mortar line to cut .

At least now when I get a quote I know what to ask ?

 

cheers ! ?

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18 hours ago, pocster said:

I presume he can’t just stick the edpm up stone !!!! 

Just check ‘he’  hasn’t already included in his quote to flash this .... if he’s looked at the job to quote you already i imagine either he’s taking responsibility for it or he’ll have looked you in the eye  and made you aware of what you’d need to provide him  so he can achieve a waterproof roof .

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Had some guys look today 

They did mention cutting in the wall to make a water proof join etc .

ive estimated the material costs are around a grand . He started at 4K!! ; needless to say I got that to drop quite swiftly .....

Should be starting next week ?

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Right !

Usual bollocks with trades ?

Anyway almost finished but he hasn’t angle grinded a slot and put trim on the rough wall to make it 100% water tight .

Just glued the edpm up the stone . It looks ‘tight’ but ‘worries’ me .

Rest of the job looks good .

Is there any easy way for me to do this for my own peace of mind ?

Rather than cut a slot etc . Was thinking of fixing like a piece of guttering / tile trim along the edge and then ‘filling’ in behind it . But what should I fill with ? . External mastik ??? 

 

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The job !

 

not quite finished so only made a part payment !

 

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Without the correct trim it will leak as the stone will get wet and it will creep down. 

 

Cut the slot and do it right !!

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Posted (edited)
8 minutes ago, PeterW said:

Without the correct trim it will leak as the stone will get wet and it will creep down. 

 

Cut the slot and do it right !!

This is what I thought!!!

 

Too be honest though the stone wall as you see it is actually above the external below ground insulation which is 150mm thick.

So 'technically' the stone wall is away from the build by some distance.....

Edited by pocster

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14 minutes ago, pocster said:

This is what I thought!!!

 

Too be honest though the stone wall as you see it is actually above the external below ground insulation which is 150mm thick.

So 'technically' the stone wall is away from the build by some distance.....

I’m probably worrying over nothing . Beneath ground has never leaked along that edge ; but niggles me . ‘Tradesmen ‘ said it couldn’t be done because there’s no way they can grind any accurate slot along the uneven wall .... I.e being lazy 

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14 minutes ago, pocster said:

Tradesmen ‘ said it couldn’t be done because there’s no way they can grind any accurate slot along the uneven wall .... I.e being lazy 

 

Screw a length of 4x2 to the wall. 9” grinder with a stone disc in it and run the guard along the timber ... not exactly rocket science .... 

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7 minutes ago, PeterW said:

 

Screw a length of 4x2 to the wall. 9” grinder with a stone disc in it and run the guard along the timber ... not exactly rocket science .... 

Yeah I agree .

Think I’ll just do it myself - less hassle!

So what do I actually stick in the slot ? Is it literally just a length of plastic trim so rain runs over the edpm rather than behind it ?

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4 minutes ago, pocster said:

So what do I actually stick in the slot

 

This stuff with a bead of sealant in the slot too. 

 

You can also bond it onto the EPDM with something like Sikaflex

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1 minute ago, PeterW said:

 

This stuff with a bead of sealant in the slot too. 

 

You can also bond it onto the EPDM with something like Sikaflex

Thanks .

from the pic it has an ‘L’ top that actually sits into the slot ?

Sad isn’t it the ‘roofer’ won’t do it , I have too ?

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Yep it’s something like a 25mm or 40mm return depending on which you choose - both are 100mm deep. For stone I would go with the 40mm on and CT1 the slot and a bead along the bottom edge too

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7 minutes ago, PeterW said:

Yep it’s something like a 25mm or 40mm return depending on which you choose - both are 100mm deep. For stone I would go with the 40mm on and CT1 the slot and a bead along the bottom edge too

Thanks ! Glad someone knows how to do it properly.... Think I might start a new thread ....... ?

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EPDM upstand at roof edge should be min 150mm high too.

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More photos of joy 

 

so in the corners do I try to overlap the metal flashing 

Also the front section ‘under’ the house ; presumably no flashing required there ??

 

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Patches are ok but really should be 270 degrees. 

 

And does that  go up the face of the house ..? If so it should have the trim too but that corner could be fun ..... 

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6 minutes ago, PeterW said:

Patches are ok but really should be 270 degrees. 

 

And does that  go up the face of the house ..? If so it should have the trim too but that corner could be fun ..... 

Here’s a better photo of the front which I guess is ok 

 

 

image.jpg

image.jpg

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So @PeterW is the main issue still the flashing ( or lack of ) ?

 

 

image.jpg

image.jpg

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19 hours ago, PeterW said:

Screw a length of 4x2 to the wall. 9” grinder with a stone disc in it and run the guard along the timber ... not exactly rocket science .... 

 

I have done quite a bit of flashing onto rough rock walls and it’s definatly harder than a nice brick wall. You will need to work out your maximum depth needed to go into the wall due to the unevenness of  the stonework, it will only be as good as the weakest link. Also I have found that cutting a single slot with an angle grinder and then pushing in the flashings leaves little room to properly seel it up. On walls like this I often take outa good 25mm -30mm slot  by 50mm deep i then build up the bace on an angle and put the flashing in and then re- mortar the hole, that way if there is any difference in expansion and contraction resulting in micro cracking then the water will not track back into the wall because of the fall. Its al lot easier if the wall is prepped first so that you have your levels all worked out. But hay ho....  done correctly the flashing will hide a lot of sins and give you a good crisp finish. Prep a whole section before starting and mock up the flashings as these uneven walls can really chuck a spanner in the works if you assume anything.....  I am not a pro and the use of fancy sealants may well be advised, this is just what worked for me. 

CAE747DF-B08F-4214-A890-774684C4D964.jpeg

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Posted (edited)
21 minutes ago, Cpd said:

 

I have done quite a bit of flashing onto rough rock walls and it’s definatly harder than a nice brick wall. You will need to work out your maximum depth needed to go into the wall due to the unevenness of  the stonework, it will only be as good as the weakest link. Also I have found that cutting a single slot with an angle grinder and then pushing in the flashings leaves little room to properly seel it up. On walls like this I often take outa good 25mm -30mm slot  by 50mm deep i then build up the bace on an angle and put the flashing in and then re- mortar the hole, that way if there is any difference in expansion and contraction resulting in micro cracking then the water will not track back into the wall because of the fall. Its al lot easier if the wall is prepped first so that you have your levels all worked out. But hay ho....  done correctly the flashing will hide a lot of sins and give you a good crisp finish. Prep a whole section before starting and mock up the flashings as these uneven walls can really chuck a spanner in the works if you assume anything.....  I am not a pro and the use of fancy sealants may well be advised, this is just what worked for me. 

CAE747DF-B08F-4214-A890-774684C4D964.jpeg

Guys are here now - adamant that flashing not required . “Going to fill the gaps on the stone wall with liquid plastic “

Probably would be fine ; probably .

Will order flashing today once they’ve gone .

 

The flashing won’t be visible as block paving goes over all this .

Edited by pocster

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