EPDM Parapet gutter

[Morticer]

Hi Folks

Help!!!

Not sure where to start! We live in a terraced house to the rear of which we are building a single story gable extension. A small part of this extension (2.7m) shares a party wall wich we have extended upwards to form a parapet wall so that is no guttering etc overhanging the neighbours property. The parapet gutter then joins the rest of the roof about 1/3 of the way up the roof as the building widens at this point.

The architect suggested we use EPDM to line the parapet gutter, which we have but I'm really not clear about how to to the intersection between the parapet gutter, the edge of the parapet wall and the rest of the roof.

The wet weather is not help either!

Many thanks

 

[freddiemercurystwin]

Got a photo? This is a right PITA and should be avoided if at all possible because they're such a pain. Lead and a good leadworker may have been the way to go.

 

[Morticer]

Got a photo? This is a right PITA and should be avoided if at all possible because they're such a pain. Lead and a good leadworker may have been the way to go.

I'm learning that fast! Again, ignorance has lead me down this route. The architect designed the gutter setup and suggested the epdm. Although I have to say it appealed to me when I looked at lead prices.

Not sure how to share a photo...

Leo

 

[Morticer]

That didn't work then!

Untitled

• Morticer
• 28 Jan 2015
• 1

Try again...

 

[freddiemercurystwin]

And any photos from a bit further away so we can see it context?

 

[Morticer]

I've only got this early one

Untitled

• Morticer
• 28 Jan 2015
• 1

 

[Mw Roofline]

Unfortunately the rubber has been cut a little short on that corner. The only way to do that corner is with 9" formflash. You'll be able to mould it around the wall. You'll need some primer and a silicone roller. It looks a bit messy but never leaks. It should really be near to 10 degrees when using primer and formflash.

 

[Morticer]

Thanks MW. I laid the membrane but the asked the guy who designed it to show me how to finish the end... He cut it too short grrrrrr! Will look to get some formflash then.

 

[ree]

OP, its a bit late in the day for you but other DIY'ers might benefit to know that the parapet gutter should be treated more or less like a chimney stack lead back gutter.

A parapet back gutter board must have a definite fall or it will pond, as yours is showing signs of. I presume that you are discharging to the left?

There must also be support to the back gutter as it goes up the roof slope a short distance. Otherwise, as can be seen in your pics, the felt will sag at the back gutter, and possibly create more ponding.

Interestingly, the pics show rippings of ply acting as eaves protectors (ie. preventing sag) on the full roof.

FWIW: if water is allowed to return round & down at the "cut-short" corner then the laths will quickly rot, & stains could appear on that corner elevation brickwork.

OP, Is that a join in the EPDM - coming unsupported in a rafter bay?

 

[Morticer]

OP, its a bit late in the day for you but other DIY'ers might benefit to know that the parapet gutter should be treated more or less like a chimney stack lead back gutter.

A parapet back gutter board must have a definite fall or it will pond, as yours is showing signs of. I presume that you are discharging to the left?

There must also be support to the back gutter as it goes up the roof slope a short distance. Otherwise, as can be seen in your pics, the felt will sag at the back gutter, and possibly create more ponding.

Interestingly, the pics show rippings of ply acting as eaves protectors (ie. preventing sag) on the full roof.

FWIW: if water is allowed to return round & down at the "cut-short" corner then the laths will quickly rot, & stains could appear on that corner elevation brickwork.

OP, Is that a join in the EPDM - coming unsupported in a rafter bay?

Hi Ree

Yes there is a definite fall and yes it will discharge to the left.

Unfortunately I didn't have an earlier picture but I have fully supported the epdm with ply that sits just below the batten level to allow any water beneath and prevent ponding. (a bit more heavy duty than the eaves protectors)

There are no joins in the epdm as yet, it is just one single piece. My problem is how to now sort the discharging end.

 

[Morticer]

I found a photo of the supporting boards, they were not finished in the photo but you get the idea... you have to tilt your head sideways I'm afraid!

The fall was 100mm over 2.7m

Untitled

• Morticer
• 29 Jan 2015
• 1

[/img]

 

[cotswoldbuilders]

That's wrong.

The board needs to be laid across the roof timbers, not between them.

Only need to go up the roof about 300mm, the rubber needs to be a lot more tidier, ie use a penny roller into the edges.

As said, the rubbers been cut short, you need to tile/slate up the first bit of roof first, then form a lead flashing on the corner, to cover the tiles.
The lead would ideally need to fit under the epdm at the end of the valley, we normally cut a recess ( router out ) back 50mm and the depth of lead, to allow the rubber to be glued over with no ridges.
All can then be finished with form flash.

Where in glos are you, any where near Cheltenham.

 

[Morticer]

Hi yes, we're in Charfield, nr wotton under edge. Bad advice from the architect who suggested this approach (and cut it too short then). Damn.

The reason he gave for the height was that it should be higher than the parapet in the case of snow melt.

Trying to picture the lead you are recommending.

Is this salvagable?

Leo

 

[Mw Roofline]

Morticer not trying to use the forum to get people work but it might be worth getting Cotswoldbuilder to have a look mate who could sort out all these niggles for u

 

[roofspecialistsLondon]

Your architect wants sacking. Is advise you to employ a roofer to carry out your box gutter for you. Do it in fibreglass, cheaper than lead and will last 40-50 years or more of installed correctly. Doing this will be cheaper in the long run. Because no offence what you have there at the moment isn't going to last