Flat roof membrane

Forums › Home Workshop DIY › Flat roof membrane

sean2017

7 posts

Wannabe Geek

#237704 14-Jun-2018 10:35

We recently noticed that our flat roof requires recoating as it started causing a bit of problem with weather tightness after heavy rainfalls.

Received two solutions from our building consultant and roofing company he works with:

Fit new timber to give the new fall and overlay with plywood and then overlay with 1.2mm butynol
Clean down the existing roof and then recoat it with traffigard which is reinforced with fiber glass mat.

The consultant believes that butynol is expected to have a longer life with minimum maintenance requirements whereas traffigard membrane requires recoating every five year(it could last 10 years if work is done properly).

Would be great to get some feedback as to which way round we would go, and why.

Thanks in advance!

1 | 2

7782 posts

Uber Geek

#2036425 14-Jun-2018 10:55

If you are choose to modify the roof to add fall, then why not go for a more durable material e.g. longrun steel? (assuming the fall will be sufficient)

Mike

wratterus

1687 posts

Uber Geek

#2036428 14-Jun-2018 10:59

Following.

sean2017

7 posts

Wannabe Geek

#2036432 14-Jun-2018 11:03

Hi Mike

It is very likely that we will put a second floor on top of that flat roof within 10 years time and that's why we don't really want to replace it with longrun steel.

Thanks

Sean

Goosey

2831 posts

Uber Geek

Subscriber

#2036459 14-Jun-2018 11:52

sean2017:

Hi Mike

It is very likely that we will put a second floor on top of that flat roof within 10 years time and that's why we don't really want to replace it with longrun steel.

Thanks

Sean

Just curious, are you sure you can simply add a second floor. i.e. assume your current foundations strong enough to handle the extra load? May as well know this now then get a few years down the track and find you cant do this without great expense and hassle (when comparing to converting to steel roof or buttnol.

MikeAqua

7782 posts

Uber Geek

#2036468 14-Jun-2018 12:06

sean2017:

Hi Mike

It is very likely that we will put a second floor on top of that flat roof within 10 years time and that's why we don't really want to replace it with longrun steel.

Thanks

Sean

I that case I woudl go for the simplest option (or even patching) as you don't need long term durability.

I have been told traffigard are hard to get on site. One guy I know (Wellignton) was told they would need $2k worth of scaffolding erected before they would even come on site

Mike

Goosey

2831 posts

Uber Geek

Subscriber

#2036495 14-Jun-2018 13:00

MikeAqua:

sean2017:

Hi Mike

It is very likely that we will put a second floor on top of that flat roof within 10 years time and that's why we don't really want to replace it with longrun steel.

Thanks

Sean

I that case I woudl go for the simplest option (or even patching) as you don't need long term durability.

I have been told traffigard are hard to get on site. One guy I know (Wellignton) was told they would need $2k worth of scaffolding erected before they would even come on site

In this climate, everyone needs scaffolding... there are a few that go rope and harness but few and far between.

mattwnz

20157 posts

Uber Geek

#2036565 14-Jun-2018 15:18

What is the roof currently? Why not use a torch on membrane such as http://nuralite.co.nz/ . We used this several years ago to replace the membrane, although the roof has not parapets or other roofs connected to it. If you are creating a slope, you may need to get a building consent and submit plans, as it may change clearances. You should check with council anyway to see what they say. You can never be too careful with this sort of thing, as doing something that required consent can create major probelms.Roofers also don't necessarily know whether you need a consent or not for certain work.

Wise

Send money globally for less with Wise - one free transfer up to NZ$900 (affiliate link).

surfisup1000

5288 posts

Uber Geek

#2036592 14-Jun-2018 16:20

sean2017:

We recently noticed that our flat roof requires recoating as it started causing a bit of problem with weather tightness after heavy rainfalls.

Received two solutions from our building consultant and roofing company he works with:

Fit new timber to give the new fall and overlay with plywood and then overlay with 1.2mm butynol
Clean down the existing roof and then recoat it with traffigard which is reinforced with fiber glass mat.

The consultant believes that butynol is expected to have a longer life with minimum maintenance requirements whereas traffigard membrane requires recoating every five year(it could last 10 years if work is done properly).

Would be great to get some feedback as to which way round we would go, and why.

Thanks in advance!

We have butanyl , pretty good, occasionally you need to seal a seam which opens (3 times over the last 10 years perhaps). Guessing the heating and cooling can cause weaker parts of seams to split .

Fred99

13684 posts

Uber Geek

#2037657 14-Jun-2018 17:36

surfisup1000:

We have butanyl , pretty good, occasionally you need to seal a seam which opens (3 times over the last 10 years perhaps). Guessing the heating and cooling can cause weaker parts of seams to split .

Our neighbour's house has butynol over ply. Their roof level is about 5m below our floor level, so I can see it easily. Same issue there - a few seams opened up, I let them know and they had them glued back down.

The house was built in the early 00s, was originally a liquid applied membrane over ply. That was a disaster, partly the membrane failed, but also it has plaster over block parapets that were inadequately flashed and internal gutters. The entire roof structure had to be replaced, the wall linings on the top floor also needed to be gutted and replaced as water ran down between the block and drywall. If the house had been timber framed, things would have been much worse. The entire roof structure was replaced, with butynol over new ply, parapets are now all capped. The owner is a structural engineer, I presume he chose the best option under the circumstances. It needs to be done properly - very expensive consequences if it's stuffed up.

mattwnz

20157 posts

Uber Geek

#2037878 14-Jun-2018 20:51

I have never had the problem with seams opening up on the two roofs I have had, but have had fixing holes poke though from the plywood substrate. I would however suggest a light grey, rather than black, as that absorbs the heat and makes the roof space really hot.

sean2017

7 posts

Wannabe Geek

#2037893 14-Jun-2018 21:52

Goosey:

sean2017:

Hi Mike

It is very likely that we will put a second floor on top of that flat roof within 10 years time and that's why we don't really want to replace it with longrun steel.

Thanks

Sean

Just curious, are you sure you can simply add a second floor. i.e. assume your current foundations strong enough to handle the extra load? May as well know this now then get a few years down the track and find you cant do this without great expense and hassle (when comparing to converting to steel roof or buttnol.

not 100% but our consultant had a look and assured us that can be easily done.

sean2017

7 posts

Wannabe Geek

#2037896 14-Jun-2018 21:57

mattwnz:

What is the roof currently? Why not use a torch on membrane such as http://nuralite.co.nz/ . We used this several years ago to replace the membrane, although the roof has not parapets or other roofs connected to it. If you are creating a slope, you may need to get a building consent and submit plans, as it may change clearances. You should check with council anyway to see what they say. You can never be too careful with this sort of thing, as doing something that required consent can create major probelms.Roofers also don't necessarily know whether you need a consent or not for certain work.

It is traffigard and reinforced with fiber glass mate.

sean2017

7 posts

Wannabe Geek

#2037902 14-Jun-2018 22:19

I heard that butynol will be long lasting if the roof is laid with a single piece which means there are not many seams or very few but not sure about my one as they are two separate sections, measurements are roughly 3x6m and 5x8m. I am not sure if liquid applied membrane would cope better.

Also another primary drawback to butynol is its appearance as most of them are black which absorb more heat. I will talk to the roofer to find out if it comes with a white or off-white.

mattwnz

20157 posts

Uber Geek

#2037905 14-Jun-2018 22:27

sean2017:

I heard that butynol will be long lasting if the roof is laid with a single piece which means there are not many seams or very few but not sure about my one as they are two separate sections, measurements are roughly 3x6m and 5x8m. I am not sure if liquid applied membrane would cope better.

Also another primary drawback to butynol is its appearance as most of them are black which absorb more heat. I will talk to the roofer to find out if it comes with a white or off-white.

It comes in several colours these days, even white I think. But there is also a light grey. But colours are proabably more expensive. Why can't they just install it directly over the existing membrane, or remove the exisiting one and then cover over it. Or is the fibreglass too friable to work with safely? I think yu want to talk to the council to find out if doing this would be a 'like for like' roofig replacement.

ZollyMonsta

3009 posts

Uber Geek

ID Verified

Trusted

#2038034 15-Jun-2018 09:02

We had an old flat roof removed last year on the flat part of our roof. New ply was first installed and butynol then laid. No issues at all and looks fine.

Check out my LPFM Radio Station at www.thecheese.co.nz - Now on iHeart Radio, TuneIn and Radio Garden

As per the usual std disclaimer.. "All thoughts typed here are my own."

1 | 2