Asphalt or felt, which is better?

[nervous123]

Just been told by several builders/roofers that my newly built extension roof is a load of cobblers. Apparently, there's no fall, the flashings are not fitted properly, the rooflight's been fitted flush to the roof with no upstand and they've only used 1 layer of green felt with gaps smeared in bitumen.

Lack of fall:

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• nervous123
• 31 Oct 2010
• 1

Flashings:

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• nervous123
• 31 Oct 2010
• 1

Felt/bitumen:

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• nervous123
• 31 Oct 2010
• 1

To have it redone i've been given 2 choices: asphalt or 3 layers of torch on felt. The quote for the asphalt is about £500 more than the other, but he says there are no joins so it's better. Would this be money well spent?

(Please note I am only undecided between the 2, so don't post a response extolling the virtues of EPDM etc.)

 

[joe-90]

I bet they were dead cheap though.

 

[SASroofer]

I would go with felt, if only because I would have concerns over how to get a proper seal with asphalt up against the plastic.

Very sorry to see a roof finished like this, the blokes who did it need stringing up!

 

[nervous123]

I would go with felt, if only because I would have concerns over how to get a proper seal with asphalt up against the plastic.

Very sorry to see a roof finished like this, the blokes who did it need stringing up!

1. Thanks for your advice. However, your point put aside, which would you say is the more longlasting/durable?

2. The 5 builders/roofers I brought in all expressed similar feelings. It's my luck that it rained heavily the first week we moved in...otherwise we'd never have realised anything was wrong with it.

 

[nervous123]

I bet they were dead cheap though.

I don't know...it was all part of the extension price

The amazing thing is that I've got the Completion Certificate from LABC! How could they have passed off this roof??

 

[SASroofer]

Asphalt is longer lasting, although as I said above, with the detail on the plastic frame of the glazing frame, asphalt really wouldn't be suitable for that detail, so really your only proper option is a 3 layer felt system, which can last upwards of 30 years if done properly.

 

[nervous123]

Asphalt is longer lasting, although as I said above, with the detail on the plastic frame of the glazing frame, asphalt really wouldn't be suitable for that detail, so really your only proper option is a 3 layer felt system, which can last upwards of 30 years if done properly.

Sorry, I must have neglected to mention that the repair job will include building a 15cm high upstand on the roof to support the rooflight (i.e. the upstand that should have been built in the first place!). That being so, would asphalt be suitable?

If yes, I'll just have to weigh up cost vs durability... price I've been given for asphalt is £500 more than for 3 layer felt.

 

[SASroofer]

In that case I would go for asphalt all day long. Although a good felt system would last atleast 30 years, asphalt done properly could last double that.

Insist on using polymer modifyed asphalt too, its the best there is.

 

[SASroofer]

Forgot to add, make sure they take the asphalt to the top of the kerb, not on to the top. Then a lead flashing dressed over the asphalt, then your windowframes can sit on the lead. If they sit the frame on the asphalt (or felt) the weight of the glass will squash it and eventually create a leak.

 

[nervous123]

Forgot to add, make sure they take the asphalt to the top of the kerb, not on to the top. Then a lead flashing dressed over the asphalt, then your windowframes can sit on the lead. If they sit the frame on the asphalt (or felt) the weight of the glass will squash it and eventually create a leak.

I'll mention it to the builder I'm considering but tbh as he is an experienced fellow with a good name, whose been doing these sort of roofs for 30 years, I'm not too concerned about how he does it...

My query was more a general one - is asphalt worth the additional outlay than felt, which you advise it is. So thanks for that (and for all your help!).

Just btw, is £3.5k a decent price.. to strip 30m2 of old felt, add firrings and new ply, build 15cm upstand for rooflight, asphalt all over?

 

[SASroofer]

Sounds like a very good price to me, there is a lot more work involved in asphalting than there is felting, more preparation ie sheathing felt and wiring up all the timber kerbs, and they then require 3 coats, this should justify the extra £500 tbh.

 

[nervous123]

Sounds like a very good price to me, there is a lot more work involved in asphalting than there is felting, more preparation ie sheathing felt and wiring up all the timber kerbs, and they then require 3 coats, this should justify the extra £500 tbh.

Thanks for all your help, SASroofer - much appreciated

 

[SASroofer]

No probs, glad to be of service