Replacing a leaky flat roof

18 Sep 2014
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United Kingdom

I have a flat roof covering the rear of our maisonette including a bathroom, kitchen and second room.

It is a zinc roof that a few years ago started to get a bit leaky. I had roofers come in do a patch up job a few times (they put some coating over a part of it) however this seems to be a short term fixes as the water is slowly ingress and I have water stains on the wall that are expanding.

I am now at a point where I need to replace the roof and need some advice in terms of best solution as I am getting conflicting advice from roofers.

I plan on staying in the current property for another 2-3 years, so need to have a fix before selling but maybe not a rolls royce solution.

Zinc as a replacement is too expensive, so it comes down to felt and rubber EPDM.

The current roof is also not insulated - so ideally would like to add insulation to make it more energy efficient.

1. What material would you recommend felt or EPDM?

2. For installing the roof the following approaches were given by the roofers:

a. Removing existing zinc tiles, inspecting the boards and replacing any not rotten, putting a layer of plywood and then 3 layers felt

b. Putting EPDM over the existing zinc roof

3. For insulation the following were recommended:

a. Warm roof - putting the insulation on top of the existing roof
b. In between cavities - lifting the boards/plywood and adding insulation between existing joists

4. How can I anticipate if there is additional damage that may need to be repaired?

With different options I am at odds in terms of what is the best so looking for honest feedback advice.

I added a few pictures to show the condition of the roof and the water stains.

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best practice is to remove the zinc cover and all the backing boards below the zinc until you expose the roof joists.
the condition of the joists and any nearby carcassing woodwork will determine what you do next - its possible 3:10 that there is wood rot present. but wait and see.

the parapet flashing, and the abutment with the pitched roof are always suspects in a roof like yours.
maybe you will need a steeper slope for you new carcassing?

a warm roof is nowadays definitely the go-to roofing.
but best that the roofer decides with you what type of covering to use.
Thanks. I had a couple of roofers come in, still awaiting quotes for a number of options.

Option 1. Repair existing - coat with the entire ACRYPOL POLYMA THREE COAT SYSTEM, fix up some seams and hope for the best.

Pros: lowest cost, I get conflicting information about condition of zinc (some say its got life left, others do not)
Cons: when I sell the property not sure if this will be an issue (i.e. buyer try to knock down value)

Option 2. Replace the zinc - with either felt, EPDM or Fiberglass. Remove any rotten boards and replace with new ones

Felt - cheaper option, preferred by most of the roofers that came. Others mentioned that does not have longevity and is prone to roofer mistakes/leaks, perception flat will not retain value due to cheap roof
EPDM - less prone to roofer mistakes as its a single sheet. Cons is that it is more expensive than felt also easy to tear etc.
Fiber - expensive not sure the benefits

3. Insulation

Option 1: leave as is (no insulation)
Option 2: Lift the boards and put Fiberglass bats between the wood planks
Option 3: Put the warm room with Kingspan. Optimal solution but would elevate the roof which would re-doing of the paraphat flashing.

Quotes I got are coming in from £1900 - £9000 so far.

Question - one of the roofers said that if changing the roof, I must install a warm roof if I was to pass building inspection. I am aware that a warm roof is a requirement for new builds, I was not aware roof updates/old builds.

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Hi - just wanted to see if people had any input on the options? Thanks
Warm roof with EPDM.
Cold roof needs ventilated, cant tell condition of zinc from photos.
Thanks. If I replace the roof and add a warm roof - do I need to get BR sign-off?

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