Keeping the water out.....roof flashing

[cheeryble]

Hi I have changed my ideas from a very nice more complicated roof to a simple roof kinda like this one.

I have two concerns.

One is that wind will drive rain under the top roof and it will enter where the roof joins the wall.

A small amount of water may also run down the lower edge of the top roof from it's top end.

In Thailand this seal is normally done with silicone gun or something like that. OK for a few years maybe.

I would like if possible a more "proper" seal.

Suggestions?

Second

The lower roof where it joins the wall.

The roof in the pic seems to have a flashing form but I don't see how it joins the wall.

My wall will be made of thermalite blocks so if necessary could have the flashing cut into it as with lead flashing back home.

Whatever.....any experience of good solutions?

ps: May as well add.

I'm considering making the main building first i.e. only with the top roof and high wall.

I was thinking of adding the next one later with a small lean to room under it if the place actually gets used as I hope. Would like a little time of using to decide if to do that or have a separate building for that room.

It occurs to me I may just stick the lower roof up anyway and if I wish i can build a room under it on a little strip foundation.

What price for a simple lower roof like that. It would be maximum 9.5m x 4m ground measurement including a metre overhang all round. Good quality 6mm coloured sheet roofing as in the picture but better brand. I guess it must include three support posts of concrete.about 2m or so high above ground.

Thanks!

Edited February 28, 2015 by cheeryble

[IMHO]

The most common way to seal a roof-to-wall junction in Thailand is creating a cement 'foot', like this:

However, this system can have problems with cracking, and generally needs some TLC every 10 years or so.

The other way is to use a self-adhesive waterproof membrane, like this:

This stuff is available in different widths and colors, and it likely what is being used on your example photo. It's not lead - I believe it's some form of butyl rubber, which gives it some stretch and formability.

Edited February 28, 2015 by IMHO

[cheeryble]

Thanks IMHO

yes I'm also not so happy about the mortar seal.

And also yes I've used the roll stuff you showed. We used to call it flashband.

It's a strip of strong polythene stuff with bitumastic underneath and a thin layer of I think it's aluminium on top.

It is actually marvellous stuff on a flat roof especially if warmed up when applying, but just looks kinda bogy for a job like this wouldn't you think.

Plus the problem of fitting to the roof corrugations....not really made for that.

I guess I'm thinking a profile and just interested if any of these are made to chase into the wall which I'd call a proper job.

[topt]

The most common way to seal a roof-to-wall junction in Thailand is creating a cement 'foot', like this:

However, this system can have problems with cracking, and generally needs some TLC every 10 years or so.

The other way is to use a self-adhesive waterproof membrane, like this:

This stuff is available in different widths and colors, and it likely what is being used on your example photo. It's not lead - I believe it's some form of butyl rubber, which gives it some stretch and formability.

OP sorry to hijack slightly

IMHO - where can you get this as I have been looking for a waterproof tape and none of the ones on sale in Homepro, mart and Watsadu say "waterproof"? They all say tearproof but show pictures being used around tiles and sealing around drainpipes etc. One of them has a metalliized finish - like this-

Cheers

[cheeryble]

topt

don't worry they are all about the same composition they are waterproof and made of aluminium foil/butyl tape/bitumen

They're available at all the usual suspects.

Make sure you wire brush or whatever your surface down to clean and solid before applying.

If it's not in the hot sun you might find using a heat gun softens the tar and really beds it down.

If you use the wife's hair dryer make sure to clean it up as black tar tangles the hair terribly.

Edited February 28, 2015 by cheeryble

[topt]

topt

don't worry they are all about the same composition they are waterproof and made of aluminium foil/butyl tape/bitumen

They're available at all the usual suspects.

Make sure you wire brush or whatever your surface down to clean and solid before applying.

If it's not in the hot sun you might find using a heat gun softens the tar and really beds it down.

If you use the wife's hair dryer make sure to clean it up as black tar tangles the hair terribly.

Thanks - she has straighteners for that

[eyecatcher]

topt

don't worry they are all about the same composition they are waterproof and made of aluminium foil/butyl tape/bitumen

They're available at all the usual suspects.

Make sure you wire brush or whatever your surface down to clean and solid before applying.

If it's not in the hot sun you might find using a heat gun softens the tar and really beds it down.

If you use the wife's hair dryer make sure to clean it up as black tar tangles the hair terribly.

I call that flashband....the poor mans lead flashing. A very versatile product and in fairness should last a lot longer here than in the uk where the temp shrinks and cracks it within 12 months.

Nornally you need a primer to apply to the surface first to give it that "stik like shit" property but best to apply it with a wooden trowel handle rounded so it doesnt rip the ally foil or puncture it.

No need for hairdryers especially when you are up that ladder its pliable enough here.

I actually think the concrete fillet foot idea is born out of laziness and lack of skill applying a proper upstand and cover flashing......then again the chances of rain penetration are nowhere near thr severity we have had to incur in our past lives.

Seriously what would we think if we saw a lead flashing here? I woukd think ey up theres a falang expecting some driving rain the nutter!

[cheeryble]

In all fairness they usually make the concrete fillets quite large dimensions....the first essential if you want it to be strong.

Still would prefer a soundly designed flashing of some sort where all top edges are themselves covered.

The photo I gave in post no 1 seems to have a flashing form but whether the top edge is concealed or just stuck on who knows.

I must go for another look.

However the bottom edge of the flashing in the corrugations seems to have a fair old gap.

[topt]

topt

don't worry they are all about the same composition they are waterproof and made of aluminium foil/butyl tape/bitumen

They're available at all the usual suspects.

Make sure you wire brush or whatever your surface down to clean and solid before applying.

If it's not in the hot sun you might find using a heat gun softens the tar and really beds it down.

If you use the wife's hair dryer make sure to clean it up as black tar tangles the hair terribly.

I call that flashband....the poor mans lead flashing. A very versatile product and in fairness should last a lot longer here than in the uk where the temp shrinks and cracks it within 12 months.

Nornally you need a primer to apply to the surface first to give it that "stik like shit" property but best to apply it with a wooden trowel handle rounded so it doesnt rip the ally foil or puncture it.

No need for hairdryers especially when you are up that ladder its pliable enough here.

I actually think the concrete fillet foot idea is born out of laziness and lack of skill applying a proper upstand and cover flashing......then again the chances of rain penetration are nowhere near thr severity we have had to incur in our past lives.

Seriously what would we think if we saw a lead flashing here? I woukd think ey up theres a falang expecting some driving rain the nutter!

eyecatcher you should come visit during a storm . Unfortunately here in Pattaya I get driving rain quite often (this mornings storm was a brief example) although to be fair I could not use lead flashing where it previously ingressed (yes I know its not a word ).

Flashing could be useful to stop the leak I now have where a sheet car port roof meets the side wall - that is what I am planning to use the tape for; covering up all the bodged silicone

[cheeryble]

There's one solution which might be done if the lower roof (the one needing a seal to the wall) is not far below the upper roof (such as in my pic in post no 1.

That is, one could line the wall with say Shera boards on battens a few inches deep and run the lower roofing sheets under the boards.

This may be the sort of application where a bit of silicone seal would work as if there were minor gaps in the silicone after a while the rain would still have to drive up the sheet a few inches.....unlikely as the gaps are likely tiny so no wind could get in to drive it upwards.

Those same gaps if used between the tops of the sheets and the wall (with no wall boards) would allow driven water in after it ran down the wall.

TOPT, this method might look better than flash band flashing and that Shera board is pretty cheap though you'd have to pay for the battens too.

Would keep the hot sun off the wall too.

Another thing i have used before which can be quite useful is a foam form which follows the roof sheet corrugations.

Back home we would use them for sealing out cold air but if glued on they could go under/behind an overlapping roof section or boards to stop rain driving upwards.

[eyecatcher]

topt

don't worry they are all about the same composition they are waterproof and made of aluminium foil/butyl tape/bitumen

They're available at all the usual suspects.

Make sure you wire brush or whatever your surface down to clean and solid before applying.

If it's not in the hot sun you might find using a heat gun softens the tar and really beds it down.

If you use the wife's hair dryer make sure to clean it up as black tar tangles the hair terribly.

I call that flashband....the poor mans lead flashing. A very versatile product and in fairness should last a lot longer here than in the uk where the temp shrinks and cracks it within 12 months.

Nornally you need a primer to apply to the surface first to give it that "stik like shit" property but best to apply it with a wooden trowel handle rounded so it doesnt rip the ally foil or puncture it.

No need for hairdryers especially when you are up that ladder its pliable enough here.

I actually think the concrete fillet foot idea is born out of laziness and lack of skill applying a proper upstand and cover flashing......then again the chances of rain penetration are nowhere near thr severity we have had to incur in our past lives.

Seriously what would we think if we saw a lead flashing here? I woukd think ey up theres a falang expecting some driving rain the nutter!

eyecatcher you should come visit during a storm . Unfortunately here in Pattaya I get driving rain quite often (this mornings storm was a brief example) although to be fair I could not use lead flashing where it previously ingressed (yes I know its not a word ).

Flashing could be useful to stop the leak I now have where a sheet car port roof meets the side wall - that is what I am planning to use the tape for; covering up all the bodged silicone

Ok yes I apologise i thought everyone lived up here in chiang mai.

You get driving rain we get toxic air for 6weeks.

I will allow you to be flippant when i ask the rest of Thailand how best to apply the 3m particle filter mask.