Hello
I hope all is well.
I have two issues I would like some advice on. Firstly, we have a flat roof extension with felt which wasn't done by roofers and have been told its been done very badly and no proper roof lights have been added either. There appears to be brown stains coming through during hot weather after weeks of no rain. Now there appears to be wet patches during rain. We think its probably a good idea to take existing felt off and re do again. Some have said just to re-felt over existing but I'm worried we will continue to get the brown spots? Can anyone explain the brown spots and why they appear on hot days?
Also, can anyone recommend any flat unopening roof lights? I have become a bit confused by looking at velux which appear to have a base and glass as separate purchases. I was hoping to purchase one unit so it would be easy for the roofers to fit.
Secondly, we have a table top roof with flat felted roof at the top and tiles on the side. There is a lot of mould in the loft and have been told this is due to lack of ventilation (there are no vents). Does it matter if vents are added in the felt or tiled part? I would be more inclined to add these to the tiled part rather than risk a leak on our flat felted roof that appears to be done to a good condition.
Thanks
Are you a tradesperson and able to answer this question?
Firstly the flat roof extension sounds to be having issues with condensation along with poor workmanship allowing ingress of water at times of rainfall.
Brown stains inside the property when we have no rainfall indicate possible standing water underneath the existing material and or also sweating between the layers caused by high temperatures. Dampness will permeate through internal walls showing brown or black staining, possibly promoting mould if not rectified.
We would highly recommend all old material was removed, the deck and joists should be checked thoroughly for any rotting or damp penetration so that appropriate action can be taken to avoid future issues.
Secondly, we can obtain roof lights from several manufacturers designed for flat roof installation, they can be easily installed and if fitted correctly can be fully guaranteed by the contractor.
Roof ventilation can be created in several ways, we would only recommend fitting fixed roof vents if clear condensation is visible. Further Assesment of the damp and mould would be needed to provide a suitable course of action to rectify the problem.
Kind regards
Damian Hession.
DSH Roofing Solutions
Answered20 June 2021
10
Anonymous user
Hi,
If this is a flat roof with felt installation and there appears to be brown stains coming through, it can be a number if things. Obviously number 1 would be a leak, number 2 would be no air flow underneath where the flat roof boarding and likely hood of being celotex touching the boards creates moisture. The best thing imo to do would be maybe rip it off and start again and re do it with a fibreglass roof and create a 50mm air flow between board and celotex maybe having to change the depth in celotex and then maybe put a over hang on the roof and install Vented soffit for the air flow, this can be expensive but if left can cause the timber to rot and be considerably more down the line.
