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Dealing With a Leaking 20-Year-old Asphalt Flat Roof

Postby booms » Tue Jul 25, 2017 10:45 am

Hi all,

I've got a flat asphalt roof terrace on a slight incline, then a section at one end that runs down at 45 degrees to a drain for a couple of feet.

It's about 20 years old, and it's been leaking intermittently for a few years.

I've painted it with various 'liquid tar' type products that have helped a bit, and we've had workmen into who have identified and fixed specific some problems (e.g. where a pipe comes through), but it seems now to be a general problem that it's reached the end of its life and needs a bigger job.

Looking around the internet I've seen some very conflicting guidance. The roof seems solid and stable, so would it be possible to:

- Put felt on top of the existing asphalt?
- Add a layer of new asphalt?
- Would all the old asphalt need to be taken up and replaced entirely?

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Postby lucylincoln » Tue Aug 22, 2017 2:13 pm

First off do you know what type of asphalt it is? British Standard Asphalt is only guaranteed to last for 10 years so if this is the one on your roof I would say it's definitely time to replace the whole roof, otherwise you're going to continually be paying a lot of money for repairs.

If it's Polymer Modified Asphalt you might get up to 50 or 60 years out of it so it would be worth spending money on proper repair work - professional roofers.

Also, if I'm not sure if you are in the position to replace it, but if so, I've found quite a helpful blog post about the different types of flat roof materials that you can choose from - including information about your current roof type.
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Postby David,roofing london » Mon Feb 12, 2018 8:59 am

Hi there.

I have been laying quality flat roofs for over 15 years for numerous councils and and major contractors, aswell as residential customers. It’s is totally acceptable to over lay your old asphalt roof if it is in a solid sound condition. You could use various applications like polyurethane cold applied roof coatings like tor,sika liquid plastics,once roof, or just bitumin prime the whole roof and get a professional roofer to lay a new felt system over it. Now if the roof does need to be stripped I wouldn’t avoid this fact and I would strip the ashpheltic and start from scratch. I’ve installed many roofs over asphalt that are totally fine get a professional honest roofing contractor to give you honest advice hope you get this sorted all the best david.
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