Flashing: please help explain

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Flashing: please help explain

Postby Sheryl » Sat Nov 04, 2017 12:59 am

I am about to replace a 20 year old fiber cement roof.

The roof that I have, has flashing along the roof ridges and I assume something at the seams (it is a big house, 4 roofs come together) though not visible because rain gutters are over them.

But as I make my way through product catalogues/brochures there seem to be a vast range of flashing types and I am frankly quite lost. The ones for the roof ridge are the only ones I understand in terms of where they go and if they are essential .

Can anyone give me a brief explanation of the following types of flashing:

"steel junction flashing”

"concrete junction flashing”

"hip capping"?

And also explain if "gable flashing” and "eaves flashing" are essential? I presume from the names that they go along the outer border of gables and at the edge of eaves, respectively, but my current roof has nothing of the sort.

I am not sure at this point if I will go with tiles or metal sheets (see other thread) but the flashing issue seems to pertain to both.
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Re: Flashing: please help explain

Postby Sometimewoodworker » Sat Nov 04, 2017 10:10 am

Sheryl wrote:I am about to replace a 20 year old fiber cement roof.

The roof that I have, has flashing along the roof ridges and I assume something at the seams (it is a big house, 4 roofs come together) though not visible because rain gutters are over them.

But as I make my way through product catalogues/brochures there seem to be a vast range of flashing types and I am frankly quite lost. The ones for the roof ridge are the only ones I understand in terms of where they go and if they are essential .

Can anyone give me a brief explanation of the following types of flashing:

"steel junction flashing”


"concrete junction flashing”

"hip capping"?

And also explain if "gable flashing” and "eaves flashing" are essential? I presume from the names that they go along the outer border of gables and at the edge of eaves, respectively, but my current roof has nothing of the sort.

I am not sure at this point if I will go with tiles or metal sheets (see other thread) but the flashing issue seems to pertain to both.


flashing:

"steel junction flashing”

This is where you have 2 different lengths of steel meeting


"concrete junction flashing”

This would be where steel roof meets a concrete wall

"hip capping"?

A hip roof has a ridge that joins in three directions

And also explain if "gable flashing” and "eaves flashing" are essential? I presume from the names that they go along the border of gables and at the edge of eaves, respectively, but my current roof has nothing of the sort.

They would depend on the design of your roof. I have gable flashings but no eave flashing

Google image search is your friend.

SSR will design your roof, as will the others I have just PMd to you.

Maybe a look through my build will help.
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Re: Flashing: please help explain

Postby Sheryl » Sat Nov 04, 2017 1:20 pm

Thanks for your help . I'm afraid I am still very unclear.

What would make a roof need gable flashing and eaves flashing? What do these things do?

The roof I currently have (fibre cement) has gables but no gable flashing, just the fibre cemenet tiles going up to the edges. Likewise it has no eaves flashing. The edge of the tiles simply go to the eaves and the gable.

I am fairly sure supplier will try to sell me the works, the question is, do I really need it? What is the purpose of these things?

And do I understand correctly that the valley where 2 roofs meet is where steel flashing would go?

Concrete flashing for where roof meets concrete - is that only if the roof ends where it meets the concrete wall? My roof extends out beyond the concrete walls by 1 meter so the ends of it never meet the concrete wall - or does something nonetheless need to go underneath at the point where the roofing passes over the concrete wall?. I may be wrong but I don't think current roof has anything of the sort, though can't be sure as might be under the eaves board,

tried to attach photo of house but can't get it to upload - will message you

I attach photos of front, side and back view of my house
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Re: Flashing: please help explain

Postby Sometimewoodworker » Sun Nov 05, 2017 7:06 am

Sheryl wrote:tried to attach photo of house but can't get it to upload - will message you


You probably need a few more posts before you can use the PM system, you may need those posts before you can upload pictures as well, I'll have to check. <begin edit -- you should be able to post pictures, however they must be jpeg format not png so that could be why you have a problem >

The section of my build that you should look at starts http://www.coolthaihouse.com/forum/viewtopic.php?f=3&t=4890&start=180 this may help and http://www.coolthaihouse.com/forum/viewtopic.php?f=3&t=3484&hilit=Sun+shade&start=30
Last edited by Sometimewoodworker on Sun Nov 05, 2017 3:10 pm, edited 1 time in total.
Reason: Pictures posting checked
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Re: Flashing: please help explain

Postby Sheryl » Mon Nov 06, 2017 7:07 pm

Thanks. In the interim since I posted this, I think I have sorted out that gable and eave flashing are optional (and not used by any house out where I live), roof ridge flashing obviously necessary as will be a type of flashing where any 2 roofs meet.

I am very unclear regarding this last in relation to 2 very large valleys that I have in my roof (result of a bad roof design followed by a retrofitted additional roof). I will again try to upload pix of what I mean. Due to the poor design the edges of the roofs do not meet, there is a space between and I assume it will be the same when the Colorbond is applied due to the underlying roof structure.

Currently what is there are very large metal gutters that go under the fibre cement tiles.

What I am not clear about is:

- does Bluescope make a flashing that would serve the same purpose? Bluescope rep in an email suggested what he called "hip capping", will that work?
-Does it get applied under or over the the roof sheets?

Thanks!

1509935969025.jpg
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Re: Flashing: please help explain

Postby Roger Ramjet » Tue Nov 07, 2017 12:18 am

Sheryl wrote:I am very unclear regarding this last in relation to 2 very large valleys that I have in my roof (result of a bad roof design followed by a retrofitted additional roof). I will again try to upload pix of what I mean. Due to the poor design the edges of the roofs do not meet, there is a space between and I assume it will be the same when the Colorbond is applied due to the underlying roof structure.

You are totally correct, it is a bad design. The question I have, is, do they serve a purpose? If not I would fill them in or lessen the angle in the valley.
When Fred had his roof done he also had valleys and ridges which appeared to be no problem to Bluescope (Colorbond) and they installed under the valleys and over the ridges as Fred submitted details of his plans to them.
I would send them a copy of the photo you posted here and see what they say, however, I have a feeling the valleys will be too steep and may cause problems in the wet.
Everyone talks about aesthetics, but have little consideration for the problems they cause and that roof will cause problems, big problems.
As far as the terminology is concerned, I went along with what the Colorbond agent used after the rep had been out and inspected the plans and bought samples with her and suggested the degree drop from one end to the other.
If they serve no purpose other than aesthetics, try and get rid of sharp angles in the valley. I made mine simple because Thais cannot handle complicated designs that may look pleasing to you, but cause all sorts of problems later. The gutting alone will not be able to withstand the amount of water coming off that part of the roof in a downpour.
I know this is not helpful, I'm talking about reality here.
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Re: Flashing: please help explain

Postby Sheryl » Tue Nov 07, 2017 11:14 am

It was not done this way for aesthetics, it was a retofit to deal with severe leaks (leak is an understatement, I had torrents of water coming in) resulting from a design that was done for aesthetics but totally impractical for the climate and direction the house faced. Original design had that whole front area where there is now a small roof open to the elements, with the house a u shape. That middle space was totally unusable as it faces south and is always either blazing sun or rain, and the rains and winds come from that direction. So next try was a flat roof with skylight to preserve the sky view, utter disaster and torrential leaks and then finally the pitched roof you see in the picture.

Unfortunately that was done sloppily, this was some 18 years ago back when I was still naive enough to think that I did not need to try to understand this stuff myself and could just hire and pay people to take care of it. That lesson has been learned!! After that leaked severely from the valleys, larger gutters were added which have worked OK. Along the way gobs of cement were placed on the roof as you can see, nto sure at what stage as it took me 5 tries (literally going through every so-called roofer in the district) before someone figured out that custom sized larger gutters were the answer.

Q: How does one go about filling them in and lessening the valley without adding new roof beams? Looking at it, I expect that the sort of U shape at the back (front when looking at the photo which was taken from the back of the house looking forward) can be made to come together and then flashing put over it but I don't see how the two side valleys can without substantial additions to the roof infrastructure? Or are there measures I don't know about?

Q: Do I understand correctly that you were able to get an actual rep from Bluescope company to come out? I have been in regular communication with them and they will answer product questions but otherwise keep referring me to supplier. Who is pretty useless. How long ago was that and who came?

Thnaks!
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Re: Flashing: please help explain

Postby Sheryl » Tue Nov 07, 2017 11:15 am

P.S. Forgot to ask who is Fred (user name?)
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Re: Flashing: please help explain

Postby Klondyke » Tue Nov 07, 2017 12:03 pm

In my own experience with this shape: there is a longitudinal metal sheet/strip under the roofing, perhaps some 20 - 25 cm overlapping underneath at each side.
No problem at an easy rain, but when there is a downpour, the water stream from one side flows very fast, reaching the opposite slope underneath upwards, flowing over the width of the strip. A U-bend at the sides of the strip would help to return the water back.
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Re: Flashing: please help explain

Postby Sheryl » Tue Nov 07, 2017 12:18 pm

Yes, that is what I currently have, retrofitted. The questions is whether to stick with that or revise the roof infrastructure as the design itself is not good. Looking for the pros and cons of revising the roof infrastructure and how
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Re: Flashing: please help explain

Postby Sometimewoodworker » Tue Nov 07, 2017 12:35 pm

Sheryl wrote:Q: Do I understand correctly that you were able to get an actual rep from Bluescope company to come out? I have been in regular communication with them and they will answer product questions but otherwise keep referring me to supplier. Who is pretty useless. How long ago was that and who came?


P.S. Forgot to ask who is Fred (user name?)


To answer in reverse order Fred was a member who inspired or influenced quite a few builds including mine http://www.coolthaihouse.com/forum/viewtopic.php?f=3&t=1698 sadly he died of cancer last year.

My roof style was designed by myself. The details of the colour bond roof, flashings, distance between purlins, site visit measurements before and after, detail of individual pieces of roof all were done by SSR last year.
IMG_2356.jpeg
Details of roof needed
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Re: Flashing: please help explain

Postby schuimpge » Tue Nov 07, 2017 2:53 pm

Sheryl wrote:Q: How does one go about filling them in and lessening the valley without adding new roof beams? Looking at it, I expect that the sort of U shape at the back (front when looking at the photo which was taken from the back of the house looking forward) can be made to come together and then flashing put over it but I don't see how the two side valleys can without substantial additions to the roof infrastructure? Or are there measures I don't know about?

Thnaks!


I have had the same problems with gutters. Contractors will come in with these barbie home mini gutters that are like 10cm deep if you're lucky...Totally inadequate for the job.

On your question of how to change this: Maybe look at taking the middle roof down and adjusting that if you really want to redo the roof extensively, but I think that it would need very deep gutters if you make them smaller, for which I guess you don't have space below where the gutter sits?! So it's a bit of a trade-off. Roof ends closer to each other, means less space for gutters which can only be compensated by making the gutters extremely deep.

Personally, I'd leave the roofing as is and still have the gutters made as deep as possible. Make sure the drains at the end of the gutters are way oversized to handle the amount of water and ensure sloping towards the drain is correct.
Flashing deep under the roof and soldered or otherwise fixed to the gutter so that no water can seep under the roof and into the house.

Cheers,
Luc
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Re: Flashing: please help explain

Postby Roger Ramjet » Wed Nov 08, 2017 12:07 am

There are a number of ways around the problem, the simplest being to lower the height of the central part of the roof, the reason for the overflow into the house is as explained, the angle of the roof is too great in the center and the overlaps under the main part too short.
You need something to break-up the flow of water and putting in guttering is the simplest. This will stop gravity from taking the water over the top of the too short lengths of material under the edges.
I would try experimentation with just one sheet of Zincalum and a bucket of water. Start with small amounts of water after bending the zincalum (flat sheet) into a a U shape, note how much water goes up the sides and adjust the angle of the bend each time until you can pour a whole bucket full of water without it spilling over the opposite edge You can also get corrugated zincalum and I'd get a flat bit and a corrugated bit. The corrugated bit will not need to be bent too much as long as the ridges run lengthways or opposite to the actual flow of the water down the sides of the ridges.
Lowering the profile or ridge of the central part of the roof will slow the flow of water further. If it's corrugated it will probably just go over the first or second bend and stop, just make sure the people installing it don't crush the ridges in the Colorbond.
The company should have corrugated Colorbond that slips under those valleys you have.
When I had my roof done the company was called Intertech Steel and they sent out a rep (female) with samples and also talked to my builder and told him exactly what they required as far as steel and spacing were concerned. I spoke with their managing director (Thai) at the time, over the phone to confirm that they had all their ducks lined up from the detailed plans. As it was they forgot to add the skirting around the whole house, but sent out another crew with that a week later.
If Bluescope keep referring you to the supplier, then it's the job of the supplier to come out and measure everything and tell you what is needed. I find it very boring when you have to do half the job yourself, which means they are Thai and couldn't care less, they just want the money. Get onto Bluescope and tell them their supplier doesn't seem interested in doing the job and I bet within a day they'll have someone out there.
You might have to custom your roof beams into steel ones, but any competent welder will be able to do that.
It's very hard to explain without using technical terms and as we all know every country calls them something different, which is why I haven't called them anything other than ridges and valleys. The lower you make that center ridge will slow the flow of water, adding corrugated Colorbond will also help.
I found Intertech Steel to be totally professional, but it sounds as though they have been taken over by a Thai company.
You can have a look at my build that might give you some ideas of what to expect, however I have a flat roof and wasn't inspired by anyone other than the fact that I built the house to last, over-engineered it, <off topic comment removed and subsequent off topic posts - Mod>
Bluescope is a reputable Australian company, which earned their reputation through Cyclone Tracy and beyond, I'm surprised they haven't got onto their agent.
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Re: Flashing: please help explain

Postby Sheryl » Fri Nov 10, 2017 1:37 pm

I have repeatedly complained to Bluescope re issues with suppliers to no avail. At this point I am about to give up, only 1 supplier found willing to come out here and after doing so and measuring the roof he has failed to produce the promised specs (5 days and counting now) AND it turned out that, contrary to what he had told me on the phone, he did nto in fact have the color I want currenlty in stock so would have to order it from Bluescope which in itself takes 1-2 weeks.

I have contacted every authorized Bluescope supplier within a day's drive of where I live as well as every unauthroized supplier I could identify. None have what I want (off-white color) in suffiicent quantities in stock and except for the one who has failed to come through with specs , none are willing to order a new roll for fear of being stuck with the left over.

So unless there is sudden emergence of specs from the supplier, I am reverting to fiber cement tiles,,assuming I can source those in white, which is also proving difficult. Only one I have identified is TPI cool series, no supplier near me. Stay tuned

None of that changes the valley gutter issue though. After much thought and discussion with the work crew decided against trying to modify the roof structure, introduces too many uncertainties plus I would have to reinstall the ceilings. Once I have a good look at the current gutter I will decide if it makes sense to put a second one above it. There are already metal sheets under the roof, but I will have a better handle on how adequate they are once the roofing is off. The current gutter seems to be in good shape and reusable according to both my workcrew and the Bluescope supplier who came out. ...though he may also just have been lazy to try to tackle the issue of making a new one.
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Re: Flashing: please help explain

Postby Sometimewoodworker » Fri Nov 10, 2017 4:07 pm

Did you manage to contact Steel and Solar or the other contact I gave you?
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