New roof advice

[Sheryl]

11 minutes ago, grollies said:

Cover the whole house instead of two roofs coming together?

Now that is a seriously huge renovation that would involve removing and reinstalling the entire roof infrastructure and I am unsure this is feasible with a roof of this size?  The original design, which was done by a US trained architect, still had 3 roofs (in a U shape with the middle unroofed) and I had assumed this was because it was not feasible/advisable to try to have a single roof of that size?

 

I just talked with my roof crew. They are enthused with the idea of redoing the infrastructure but what they are proposing is the dismantle the 2 middle roofs and replace with one middle roof that meets the roofs on either side a bit further up so less slope. Will post their sketch once done. But does this make sense? It would then be like this, both front and back, with 2 seams on either side of the middle roof:

 

[Kwasaki]

14 minutes ago, Sheryl said:

But I was told eaves flashing does not seal the eaves???

 

What my work crew is suggesting is to put in a wood board cut to the shape of the roof profile - I think yo uwould call it a batten?

It does seal if used with a foam profile filler which can be site fabricated from a suitable rubber or foam material if they are not ready available from the roof supplier who should stock them anyhow.

Steel eaves flashing with a profile filler shaped to the roof corrugation profile in place will be cheaper than wood also not in need of constant maintenance and not eventually eaten.

[Kwasaki]

22 minutes ago, Sheryl said:

The original design, which was done by a US trained architect, still had 3 roofs (in a U shape with the middle un-roofed) and I had assumed this was because it was not feasible/advisable to try to have a single roof of that size?

No it was architectural design use in hot climates. 

[Sheryl]

43 minutes ago, Kwasaki said:

https://www.google.co.th/search?q=images+of+roof+valley+details&tbm=isch&tbo=u&source=univ&sa=

X&ved=0ahUKEwjkruHU16vXAhVKrI8KHZU6DdEQsAQIJQ&biw=1094&bih=522

What shows there under "box valley gutter" is exactly my current arrangement. Which works. What I am having trouble getting a handle on is how much difference it would make to go for one of the alternatives, all of which would entail substantial work.

 

From discussion just now with my workers,  going from 4 to 3 roofs (bringing the back roof forward) would require replacement of ceilings as well,  including one recently replaced at considerable expense and aggravation. I think this is just too much, given that the current arrangement, while jerry-rigged, does work.

 

Other alternative would be to just make the front middle roof larger and higher with more gentle slope such that it directly meets the roofs on either side, further up. Would  still have a V shape but no space between the roofs, and the slope from the middle roof would be more gentle. I  assume then apply what Bluescope calls "hip capping atop those seams, and maybe metal sheeting under. This can be done with minimal ceiling revision but the question is, will it be worthwhile/help?

 

 

[Sheryl]

57 minutes ago, Kwasaki said:

The reason no leaks was using a concrete sealing mix and mastic at roof eaves where it was in contact with the gutter l believe you mentioned early on, that does serve purpose as in your case but if the gutter had been the correct design initially it wouldn't of caused a problem.

OK, well if we stay with the current design will in any case need to remove and replace the gutter, so what is it that needs to be done differently this time? I cannot tell from the google image how different from what I have currently.

[simoh1490]

I'm way out of my depth on this one! What I will say though is that redesigning an entire roof is not something that's easily done without first comprehensively knowing the loading and design characteristics of the structure it sits on and the materials it incorporates - personally, I wouldn't even think about doing it unless a structural engineer or a design architect was involved somewhere in the process.

[Sheryl]

6 hours ago, grollies said:

All the drawings are on PDF, you don't need a CAD programme to view them. I had a look at a couple and they're pretty good tbh.......

Sorry to seem so stupid (in this field of expertise, I am..or at least, ignorant) but can you tell me which files you refer to? All the ones I clicked on were *.dwg

[Sheryl]

1 minute ago, simoh1490 said:

I'm way out of my depth on this one! What I will say though is that redesigning an entire roof is not something that's easily done without first comprehensively knowing the loading and design characteristics of the structure it sits on and the materials it incorporates - personally, I wouldn't even think about doing it unless a structural engineer or a design architect was involved somewhere in the process.

 

Thank you, Simoh. There is also the fact that this is not a new construction but a very much lived in house, full of furniture and even some large statue antiquities on both levels and one I need to keep living in while the work goes on...and even trying to move myself and everything else to ground floor would be a huge, huge hassle.

 

Complete roof redesign is simply not on.

 

I think we are down to 2 options:

 

1 - stay with original design and tweak it through better installation, i.e. (a) in the back have the sheets meet (?or overlap?) and cover well with appropriate flashing, metal sheet perhaps underneath as well, (b) improved gutter installation (once I know what it is that requires)

 

2 - minor modification to the small front middle roof only , making it higher and coming out further at gentler slope such that it intersects the side roofs further up, with hip capping applied - the questions is, how much difference will that make? Will I not still need gutters in the resulting V? My work crew, who do not pretend to be architechs and are just going by  their collective experience tell me it would help but  "just a little".

 

Thoughts?

 

 

[Sheryl]

53 minutes ago, Kwasaki said:

It does seal if used with a foam profile filler which can be site fabricated from a suitable rubber or foam material if they are not ready available from the roof supplier who should stock them anyhow.

Steel eaves flashing with a profile filler shaped to the roof corrugation profile in place will be cheaper than wood also not in need of constant maintenance and not eventually eaten.

OK, you are converting me...and I suspect some sort of profile filler such as you describe is what supplier meant when he said he will come up with "something" to address the critter entrance issue. But will not foam or rubber filler be liable to be chewed through by rats? I have certainly known them to eat through both foam and rubber...

[grollies]

10 minutes ago, Sheryl said:

Sorry to seem so stupid (in this field of expertise, I am..or at least, ignorant) but can you tell me which files you refer to? All the ones I clicked on were *.dwg

The list of drawings are CAD and most of them have a duplicate pdf drawing but not all (and tha ones you want probably won't have an associated PDF file in my experience...).

 

I'd be asking for installation drawings in any case, what are you supposed to do, guess?

[simoh1490]

10 minutes ago, Sheryl said:

 

Thank you, Simoh. There is also the fact that this is not a new construction but a very much lived in house, full of furniture and even some large statue antiquities on both levels and one I need to keep living in while the work goes on...and even trying to move myself and everything else to ground floor would be a huge, huge hassle.

 

Complete roof redesign is simply not on.

 

I think we are down to 2 options:

 

1 - stay with original design and tweak it through better installation, i.e. (a) in the back have the sheets meet (?or overlap?) and cover well with appropriate flashing, metal sheet perhaps underneath as well, (b) improved gutter installation (once I know what it is that requires)

 

2 - minor modification to the small front middle roof only , making it higher and coming out further at gentler slope such that it intersects the side roofs further up, with hip capping applied - the questions is, how much difference will that make? Will I not still need gutters in the resulting V? My work crew, who do not pretend to be architechs and are just going by  their collective experience tell me it would help but  "just a little".

 

Thoughts?

 

 

My thoughts are that Option 2 is guesswork and a lot of extra work which may or may not produce results, the risk is higher than the potential payback so I would abandon the idea, but that's just me.

 

Option 1 is proven so I would go with that, improving the quality of installation as I went along. Most of the work is straightforward, the metal sheets need to overlap each other which the workmen know so the risk is to the 5% of the roof where roofs meet and where the roof meets flashings and valleys. As long as your crew focusses on those potential problem areas and gives thought and care to them, I think it will all work out OK. The biggest single issue is the two large valleys that overhang the front of the house, if you reuse the existing ones, as long as they are in good condition, you will be fine - if they have to be replaced, just ensure they are equally as big and strong, if not bigger and stronger.

 

 

[wayned]

In order to redo the guttering/valleys properly you will need someone with the equipment to properly braze/solder galvanized sheet metal and knows what they are doing..  Effectively he will be building a large irregular shaped galvanized bath tub with the sides extending under the roof to retain any run off otherwise the "bathtub" will overflow and you will, get water inside.  You said that your "crew" has no welding equipment so I doubt the they know what is required.

[Sheryl]

Thanks Simoh, very clear and sensible reply. In the interim the eork crew, having had time to think things through, came back to me and said that in option 2 it might just leak in a slightly different location than before (i.e. in the new valleys). So basically what you said.

 

Decided: we stay with the current, admittefly bad, design and current box gutter solution for same.

 

I might not feel more confident of roof redesign even if I had an experienced architect and "real" roofer advising it...because an experienced architect and roofers are who created this mess in the first place.

 

 

 

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[simoh1490]

4 minutes ago, wayned said:

In order to redo the guttering/valleys properly you will need someone with the equipment to properly braze/solder galvanized sheet metal and knows what they are doing..  Effectively he will be building a large irregular shaped galvanized bath tub with the sides extending under the roof to retain any run off otherwise the "bathtub" will overflow and you will, get water inside.  You said that your "crew" has no welding equipment so I doubt the they know what is required.

There's quite a difference between welding and soldering/brazing, even the chap who did my rainwater gutters has simple brazing tools and he did a pretty good job. Your point however about it needing to be done properly is of course entirely valid, one solution might be to leave the existing valleys in place, regardless of their condition and fabricate the second valley over it using the original as a form - there's no indication that the valleys need to be a different shape or size from present since they haven't leaked for some time, there's no reason however why the new second skin of valley couldn't be made with taller sides if needed. Just an idea, you'd really need to be there and see it to understand if it is reusable or if it needs modification, perhaps we can get a photograph when we get to that point?

[Kwasaki]

23 minutes ago, Sheryl said:

Other alternative would be to just make the front middle roof larger and higher with more gentle slope such that it directly meets the roofs on either side, further up. Would  still have a V shape but no space between the roofs, and the slope from the middle roof would be more gentle. I  assume then apply what Bluescope calls "hip capping atop those seams, and maybe metal sheeting under. This can be done with minimal ceiling revision but the question is, will it be worthwhile/help?

To try and explain can be difficult but nevertheless l can guess what they would like do but making the middle roof is incurring unnecessary work IMO.

The existing valley gutter could be left in place and just cleaned off of cement and debris the existing middle roof structure could left too.

Hope following sketch explains :- 

13 minutes ago, Sheryl said:

But will not foam or rubber filler be liable to be chewed through by rats? I have certainly known them to eat through both foam and rubber...

Use an inverted metal flashing cut to suit :-

 

Gotta go pick Mrs up.

Will answer questions on sketches later if any.

[Sheryl]

In order to redo the guttering/valleys properly you will need someone with the equipment to properly braze/solder galvanized sheet metal and knows what they are doing..  Effectively he will be building a large irregular shaped galvanized bath tub with the sides extending under the roof to retain any run off otherwise the "bathtub" will overflow and you will, get water inside.  You said that your "crew" has no welding equipment so I doubt the they know what is required.

Ok so just soldering into place. Is that soldering to the roof sheets or the purlins and rafters? As if the former I need to check with Bluescope. May be an issue. Not supposed to allow vontact of that sort to other metals.

Actually turns out they do have welding equipment.

Why is it that when people hear "Cambodian worket" they assume ignorance and incompetence? These are the brightest group of contractors I have ever worked with. Recently re-roofed a small garden house for me and did perfect job that has weathered torrential rains without problem.

The foreman has overseen complete construction of multiple houses and has about 20 years experience, most if it in Thailand.

I just didn't think they had brought that gear with them.

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[simoh1490]

3 minutes ago, Kwasaki said:

To try and explain can be difficult but nevertheless l can guess what they would like do but making the middle roof is incurring unnecessary work IMO.

The existing valley gutter could be left in place and just cleaned off of cement and debris the existing middle roof structure could left too.

Hope following sketch explains :- 

Use an inverted metal flashing cut to suit :-

 

Gotta go pick Mrs up.

Will answer questions on sketches later if any.

I like the top drawing and the associated idea, very very very much indeed.

 

 

[Sheryl]

"... Gotta go pick Mrs up.

Will answer questions on sketches later if any."

 

 

In first sketch, what do the 3 bottom u shaped figures represent? The top one I know is the gutter.

 

 

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[simoh1490]

The top one is a cross section of the (two) large valleys. It suggests leaving the existing valley in place and placing a larger new valley over it, the steel sheet of the roof would then overlap both valleys.

 

I'm still working on understanding the bottom one!

[wayned]

5 minutes ago, simoh1490 said:

I like the top drawing and the associated idea, very very very much indeed.

Me too!

7 minutes ago, Sheryl said:

Why is it that when people hear "Cambodian worker" they assume ignorance and incompetence? These are the brightest group of contractors I have ever worked with. Recently re-roofed a small garden house for me and did perfect job that has weathered torrential rains without problem.

I never said anything about Cambodian workers, I built my house using Thai farmers!  You're the one that said that they didn't have the equipment.  I guess that I will butt out now and go have two pints!

[Sheryl]

Sorry, didn't mean to offend. I overreacted to the quotes around "crew".

 

My apologies.

 

[emoji120]

 

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[Sheryl]

New question -- the radiant barrier if bought in rolls of 1.25 m length is by my caculations going to cost something like 150k baht. Can that possibly be correct? Am I missing something? Can it be sourced in larger roles?

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[simoh1490]

Just now, Sheryl said:

New question -- the radiant barrier if bought in rolls of 1.25 m length is by my caculations going to cost something like 150k baht. Can that possibly be correct? Am I missing something? Can it be sourced in larger roles?

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Somethings not right there. I know radiant barrier from Homepro to be 60 metres by 1.25 metres, that's 75 square metres per roll for about 1,800 baht. 150k baht would buy enough RB to cover 6,225 square metres or enough RB to encase a small town in Laos! 

[Sheryl]

AHA --I knew something had to be wrong but did not know what.


60 meters , in my frazzled state I thought it was 0.60 meters width. As Gilda Radner used to say "never mind".....

Fairly major personal/family crises arose in past 48 hrs so I am working on too little sleep...

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[simoh1490]

15 minutes ago, Sheryl said:

AHA --I knew something had to be wrong but did not know what.


60 meters , in my frazzled state I thought it was 0.60 meters width. As Gilda Radner used to say "never mind".....

Fairly major personal/family crises arose in past 48 hrs so I am working on too little sleep...

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Hope it all works out OK, in the meantime, just keep asking your questions as and when you need to.

[grollies]

1 hour ago, wayned said:

Me too!

I never said anything about Cambodian workers, I built my house using Thai farmers!  You're the one that said that they didn't have the equipment.  I guess that I will butt out now and go have two pints!

Thai farmers are great builders. Take my garage wall for instance. The garage floor slopes front to back and I asked him to keep the low wall level.

[grollies]

Khun Daeng in surrealist mode.

[grollies]

Anyway, this topic is way over my head.........

 

I'll get my coat.

[Kwasaki]

4 hours ago, Sheryl said:

"... Gotta go pick Mrs up.

Will answer questions on sketches later if any."

 

In first sketch, what do the 3 bottom u shaped figures represent? The top one I know is the gutter.

 

The 'U' shape is your existing valley eave purlins.

The rafters detail is omitted.

The new flashing sits on the valley eaves purlins.

Your old gutter could stay place.

To construct a ' V ' shape roof in this location where can they fix let alone stand.

Hence my suggested detail. 

[Kwasaki]

4 hours ago, simoh1490 said:

The top one is a cross section of the (two) large valleys. It suggests leaving the existing valley in place and placing a larger new valley over it, the steel sheet of the roof would then overlap both valleys.

 

I'm still working on understanding the bottom one!

Firstly you got it.

 

Secondly l could do a sketch for you to understand the on site forming of a steel eaves profile flashing using snips but l only have "Paint" as a computer drawing facility.

Using a small off-shelf 90% steel flashing which are available out where l am so not hard to find,  you place a roof sheet upside down on a bench, you place angle flashing against the end of the profiled roof and mark the corrugation profile of the sheet on the angle flashing.

You then get left & right gibows or you can use ordinary tin snips to cut the angle so it fits the underside of the corrugations of the roof sheet the same as a profile foam filler would.

To cut galvanized roofing materials as in good practice you should use only snips or a steel roof shearing tool not an angle grinder with a steel disc blade.