Ponding on new flat roof above bay window & dormer

kn_homes

Hi All,

I recently got new slate roof and along with it new flat roof above the bay windows at the front and new flat roof above the dormer at the rear.

It's been less than 1-2 weeks since the work was completed and as you can see from the pictures below I have standing water ('ponding') on the flat roof. Pictures were taken a day after the rain.

The roofers did remove all of the felt layers from previously, changed the OSB to new ones and then applied the rubber membrane on top of OSB.
From my limited knowledge/research I done so far, it appears that correct 'fall' has not been put in place.

Could you please comment on this - is my expectation wrong (or) is this a botched job ?
Also what are your thoughts on the felt membrane in the gutters - is it normal ?, I'm being told this situation is normal and does affect the life of the roof !









Thanks
KN

Swipe

A little standing water on a rubber roof is perfectly normal and nothing to be concerned about. Some roofers will even include this as a note in a disclaimer.

Tucosalamanca

One word - shocking.

The fall is incorrect but that's only one of a number of issues.

The detailing (where new rubber meets the older roof) looks terrible from the photo.
Other than the low cost, I can see no reason why they chose to install rubber anyway, there are far better products for the task.

The roofing membrane should not be hanging in the gutter like that. Eaves trays should have been installed (they cost very little) the fact that membrane has not even been cut back says to me that they're cowboys.

The older slated section has had repairs carried out, but even that's sloppy (and unfinished) in my opinion.
They haven't even cleared debris from the valley gutter for inspection and part of the plastic guttering also hasn't been cleared.

The roof as it stands, has got future problems written all over it.

I'm assuming that you're working on a limited budget, because in all honesty, everything in the photo should have been replaced when the scaffolding is in place.

kn_homes

Tucosalamanca said:

One word - shocking.

The fall is incorrect but that's only one of a number of issues.

The detailing (where new rubber meets the older roof) looks terrible from the photo.
Other than the low cost, I can see no reason why they chose to install rubber anyway, there are far better products for the task.

The roofing membrane should not be hanging in the gutter like that. Eaves trays should have been installed (they cost very little) the fact that membrane has not even been cut back says to me that they're cowboys.

The older slated section has had repairs carried out, but even that's sloppy (and unfinished) in my opinion.
They haven't even cleared debris from the valley gutter for inspection and part of the plastic guttering also hasn't been cleared.

The roof as it stands, has got future problems written all over it.

I'm assuming that you're working on a limited budget, because in all honesty, everything in the photo should have been replaced when the scaffolding is in place.

The older part is my neighbours roof, so that was not worked upon by my roofers.
What should my roofers have done ideally in this situation when bridging between my neighbours roof and my roof ?

kn_homes

And for full context, below are the details mentioned in the roofer's quote - so I'm just trying to get clarity/feedback on whether the work that has been done is to correct standards and as per what has been quoted.

QUOTATION

Flat Roof Renewal Front/Rear × 2:

1. Strip original flat roof (front & rear) of membrane & boarding.
2. Supply & fit 75mm PIR insulation between rafters.
3. Supply & fit 18mm OSB board to flat roof area.
4. Supply & fit Primer to roof deck surface.
5. Supply & fit 50mm x 25mm drip edge batten.
6. Supply & fit Resitrix rubber roofing membrane.
7. Supply & fit kerb trim.
8. Supply & fit drip edge trim.
9. Remove all debris from site.

Tucosalamanca

The best solution would have been reach agreement with the neighbours and have both done at the same time, ideally, with additional insulation being added to both.
It's hard to see from the photo, your roofer appears to has sealed the new rubber to the existing roof material next door, this will always be a weak point in the installation. Differing flat roof materials rarely work well together.
Your roofer could have elected to use the same material as next door, this offers the best chance of creating a watertight joint. It's possible that they used Resitrix and welded it to next door's felt. This would be better but still not ideal.
They could have formed an upstand (using mop roll or similar) to at least reduce the risk of a leak developing.
If they've just relied on adhesive and sealant, it's unlikely to be a lasting solution.

Resitrix and rubber are two entirely different products and systems.
Rubber is similar to bicycle inner tube, Firestone and Classicbond being two of the big brands.
Resitrix is a bitumen reinforced EPDM (and also several times the price). The fact that they've mentioned primer, suggests Resitrix but I can't tell from the photos.
If you want to check, rubber is smooth to the touch, where as Resitrix has a textured woven feel to it.

Felt in the gutter will lead to accelerated moss build up, which will lead to overflowing gutters, damp walls and so on.
It's certainly not good practice nor is it normal.
I wonder if the bottom course of tiles have been set correctly, or if the membrane is hiding the fact that the installation is wrong? Tiles should hang around 50mm in to the gutter (your final photo suggests otherwise).

kn_homes

Some progress today:
1. Roofer is going to come back and fix the rear flat roof ponding issue by putting in furrings and then osb board on top and cover it up with Resitrix Rubber layer
2. Push Eaves protector underneath the felt and fix it in place with adhesive and cut excess  felt back

I'm hoping this will sort things out - is there anything else worth mentioning/ to watch out for when the works takes place/finish. 

Thanks in advance, will upload new pics once fixed

DansAdvice85

There should be no standing water on the roof as ultimately it will shorten the life of your roof and the drip edge is way to long it should have been cut back this will slow the flow of rain water and not let little debris that would usually pass through the downpipe to collect and back up the gutters making blockages more regular.