flat roof just over 2 years old, but told to replace it because we walk on it!

  anonymouscoward2012b 12:07 12 Jul 2014

Just over 2 years ago we had our flat roof totally replaced. It now consists of 3 layers of bitumen paper. On top of that is tanalized wood supporting composite, 25 year lifespan, composite decking.

A builder has told us we should not walk on bitumen paper flat rooves even though we are really walking on decking supported by wood on 3 layers of bitumen paper.

We are disappointed we are being told to replace a flat roof with no reported problems just because he occasionally walk on it.

Is this advice correct?

  spuds 12:22 12 Jul 2014

Not the answer you are seeking, but we have flat roof's on some outbuilding's, which people tend to walk across on occasions. Looking at some of the markings that are left behind, cannot be doing the roofs any good. We tend to find the problem appears much worse on a hot day, which I suspect is the bitumen,roofing adhesive and felt covering 'heating up' slightly?.

  wee eddie 18:16 12 Jul 2014

Is it possible that your new roof is not designed to be "load bearing" and the recommendation has nothing to do with it's ability to be waterproof at all

  BRYNIT 00:35 13 Jul 2014

I've never known a flat roof that could not be walked on. When I worked as a sky installer we had to use metal plates to walk on not because we would damage the roof but to prevent us from falling through as our weight would be distributed over a larger area.

This may give you some info on flat roof CLICK HERE

A small sections

Flat roofs tend to be sensitive to human traffic. Anything which produces a crack or puncture in the waterproofing membrane can quite readily lead to leaks. Flat roofs can fail, for example; when subsequent work is carried out on the roof, when new through-roof service pipes/cables are installed or when plant such as Air Conditioning Units are installed. A good roofer should be called to make sure the roof is left properly watertight before it is left. In trafficked areas, proper advisory/warning signs should be put up and walkways of rubber matting, wooden or plastic duck-boarding etc. should be installed to protect the roof membrane. On some membranes even stone or concrete paving can be fitted. For one-off works, old carpet or smooth wooden planks for workers to walk or stand on will usually provide reasonable protection.

You might want to get a second opinion.

  carver 09:18 18 Jul 2014

You say that you have "3 layers of bitumen paper" just exactly what are these 3 layers.

You should have 1 layer of underfelt that is nailed down, one layer that is laid on top of that that is either cold fixed or hot fixed, then a top layer of green mineral high performance felt is added to finish.

If these layers have been put down correctly and then a suitable decking with plenty of contact points you should be OK, just as long as you do not have chippings added and it goes without saying the roof construction should be able to withstand load bearing.

In a perfect world you would have a rubber roofing systems installed but it's not cheap.

How much is this builder quoting to remedy your "problem".

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