New roof advice

[Sheryl]

What time of day?
Windows/doors open or closed?
 
Also, if you have a chance, how many square metres is your roof, useful to confirm ventilation sizes later.

Sorry forgot to mention!
3 pm
Windows open

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[Sheryl]

When you are ready to remove the old roof, PM me.  I will do some laundry and wash the truck.  That way all of the rain in SEA will be centered over my house in Nakhon Sawan Province!

Thanks -- good plan. I am also googling "anti rain dance" !

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[simoh1490]

Sheryl: can you please take another temperature reading for us, this time on the floor of the attic (at the same time of day as the others above) in a part of the roof that incorporates RB and vented soffits? I would not expect your attic temperatures to be reduced as a result of your new roof, cooling the attic is NOT your objective and none of the things you are doing will achieve that. Your objective is to A) prevent radiant heat from hitting the attic floor,  preventing hot air from penetrating through the attic floor and C) creating ventilation and airflow in your attic/roof void. If all goes to plan you should see the upper part of your attic remaining very hot, the lower part, the bottom foot or so, should however be quite cool.

Edited November 17, 2017 by simoh1490

[Sheryl]

Great baseline data. Be interesting to see how this changes as you progress.
With that shower, did you find out if the un-foiled outside section is waterproof?

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You mean on the RB? No as so far installed only in the worker's house with roof intact. Anyhow I went with 2 sided foil.

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[Sheryl]

Sheryl: can you please take another temperature reading for us, this time on the floor of the attic (at the same time of day as the others above) in a part of the roof that incorporates RB and vented soffits? I would not expect your attic temperatures to be reduced as a result of your new roof, cooling the attic is NOT your objective and none of the things you are doing will achieve that. Your objective is to A0 prevent radiant heat from hitting the attic floor,  preventing hot air from penetrating through the attic floor and C) creating ventilation and airflow in your attic/roof void.

Once in I will. So far these are in place only in the workers house and I did not think to get baseline temp there beforehand.
Rained again yesterday and looks poised to today...

New question: I gather that the screws used to affix the roofing come in djfferent qualities and that I should get class 3 or better. Can anyone advise how to tell? Everywhere I have checked has only 1 type of screw and did not know what I was fslking about. No "class" indicated on the boxes the screws come in. ???

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[Kwasaki]

2 hours ago, simoh1490 said:

  preventing hot air from penetrating through the attic floor

This is prevented and greatly reduced by installing rockwool/fibreglass at a minimum of 150 mm depth on the ceiling area of the attic/loft area.

[simoh1490]

2 minutes ago, Kwasaki said:

This is prevented and greatly reduced by installing rockwool/fibreglass at a minimum of 150 mm depth on the ceiling area of the attic/loft area.

Yes agreed, although the installation of RB also helps with that because heat is no longer being radiated at the roof floor, by the roofing material.

 

And to be clear, the rockwool insulation only slows down the transfer of heat to the ceilings below, it doesn't prevent it, if it gets hot enough for long enough, it will be defeated.

[carlyai]

Hello Simoh1490,

Why would you not expect the attic temperature to be reduced with the new white roof?

If the temperature is not reduced with the white roof, why install a white roof? Would any color have done?

Not questioning you, just I don't know.

Also are you saying because of the different cooling factors that come into play in keeping the bottom foot of the attic cool, it is better to have a large attic space rather than a small attic space; even though with a large attic space you will have more air to get hot?

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[Kwasaki]

18 hours ago, scorecard said:

Thanks for that.

Were you able to buy any type of canopy, or whatever the right term is to put over the downlights so that the insulation (the plastic bag) isn't in contact with the lights? 

No l didn't bother because my insulation is foil covered as posted before, lighting fitments are cooled by the internal room when switched on in the room with air-con.

My upstairs & bedroom downlights with 1 main central light are all fluorescent light and have a fire hood covering on the internal ceiling side.

 

If your installing plastic type covered ceiling insulation that will need a canopy of some  description if your ceiling lights do not have a fire hood maybe improvise with straining colander used in cooking. 

[Kwasaki]

43 minutes ago, simoh1490 said:

Yes agreed, although the installation of RB also helps with that because heat is no longer being radiated at the roof floor, by the roofing material.

 

And to be clear, the rockwool insulation only slows down the transfer of heat to the ceilings below, it doesn't prevent it, if it gets hot enough for long enough, it will be defeated.

Yeah !!  don't want to get into it too much because of different installations & situations in builds.

Foil covered rockwool/fibreglass is and can be adequate. 

[scorecard]

2 hours ago, Kwasaki said:

No l didn't bother because my insulation is foil covered as posted before, lighting fitments are cooled by the internal room when switched on in the room with air-con.

My upstairs & bedroom downlights with 1 main central light are all fluorescent light and have a fire hood covering on the internal ceiling side.

 

If your installing plastic type covered ceiling insulation that will need a canopy of some  description if your ceiling lights do not have a fire hood maybe improvise with straining colander used in cooking. 

 

I'll use your suggestion re ..."..straining colander used in cooking." Thank you.

 

- I'm assuming your meaning steel or aluminium rather than plastic?

 

This sounds like a silly point - just checking. 

[simoh1490]

Another advantage of LED's over the alternatives, they run cold so fire risk is vastly reduced. 

[Kwasaki]

28 minutes ago, scorecard said:

I'll use your suggestion re ..."..straining colander used in cooking." Thank you.

I'm assuming your meaning steel or aluminium rather than plastic?

This sounds like a silly point - just checking. 

Plastic if heat proof, there are fire hoods available in the west but maybe available in Bkk, @Crossy could probably help you more.

[carlyai]

Another advantage of LED's over the alternatives, they run cold so fire risk is vastly reduced. 

Sorry to be a cold blanket, but LED lights are still powered from 220v so if the electrical work is shoddy and foil is used there is still the electrocution risk. Fire risk is debatable.
Depends on the contractor.

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[simoh1490]

10 hours ago, carlyai said:

Sorry to be a cold blanket, but LED lights are still powered from 220v so if the electrical work is shoddy and foil is used there is still the electrocution risk. Fire risk is debatable.
Depends on the contractor.

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Sure the voltage doesn't change but the operating temperature of the bulb and the fixture remain very low if not cold. So as long as care is taken to buy fixtures that have recessed and secure wiring connections the risk from fire is virtually non-existent. My house was rewired about two years ago and it contains mostly downlighters in each room, since I have quite deep insulation on the attic floor this was an aspect that we looked at very closely. Initially, I used sections of 4 inch blue pipe as a protective casing to separate the insulation from the light where the yellow conduit fed directly into the ring of blue pipe, subsequently I dispensed with the blue pipe altogether. I did, however, run tests to see if I could get the kraft paper casing that covers the insulation to burn and/or conduct current and I couldn't, despite shorting a circuit directly to the foil/kraft paper the best I could get was a small burn hole that wouldn't spread. That's not to suggest it cannot burn or conduct electricity, it's just that I couldn't manage to do it easily.

[Sheryl]

Hi Guys

 

Some new questions in the optimistic hope of being able to start this work sometime in the near future (Still raining here....!)

 

1. Screws:  I don't remember if it wtas in this (now epic length) thread or elsewhere but I picked up the idea that there are different qualities of screws for roof tiles and that I needed to be sure to get "Class 3" or better.

 

Can't find them anywhere - all the suppliers here have but 1 type of screw and it has no class specified.

 

Something to worry about or not? The screws available have the rubber washer at the head and are copper coated (or coated with something of copper color). ??

 

2. Sealant: You may recall that infamous part of my roof with the retro fitted small 4th gabled roof creating huge valleys. (If not, see below).  I have now been able to get a shot from inside the roof of the valley gutters, see below 2nd pix. Looks like the lips are pretty wide but also looks to me, like critters can get into the attic by going under the tiles and around the gutter. (In fact I now understand the incredible banging noises the bats and squirrels made coming in). Is there any particular product recommended to use as sealant around things like this (e.g. where the roof tiles meet the valley gutter and around sides of the valley gutter? I think in the past they used silicone. May have also slapped some concrete around. I'd  like to find something long lasting (and, obviously, waterproof). And non-toxic once dry. It isn't going to do much good using eaves filler if this avenue of egress remains.

 

Inside view:

 

Thanks!

 

[carlyai]

Hi Guys
 
Some new questions in the optimistic hope of being able to start this work sometime in the near future (Still raining here....!)
 
1. Screws:  I don't remember if it wtas in this (now epic length) thread or elsewhere but I picked up the idea that there are different qualities of screws for roof tiles and that I needed to be sure to get "Class 3" or better.
 
Can't find them anywhere - all the suppliers here have but 1 type of screw and it has no class specified.
 
Something to worry about or not? The screws available have the rubber washer at the head and are copper coated (or coated with something of copper color). ??
 
2. Sealant: You may recall that infamous part of my roof with the retro fitted small 4th gabled roof creating huge valleys. (If not, see below).  I have now been able to get a shot from inside the roof of the valley gutters, see below 2nd pix. Looks like the lips are pretty wide but also looks to me, like critters can get into the attic by going under the tiles and around the gutter. (In fact I now understand the incredible banging noises the bats and squirrels made coming in). Is there any particular product recommended to use as sealant around things like this (e.g. where the roof tiles meet the valley gutter and around sides of the valley gutter? I think in the past they used silicone. May have also slapped some concrete around. I'd  like to find something long lasting (and, obviously, waterproof). And non-toxic once dry. It isn't going to do much good using eaves filler if this avenue of egress remains.
 

Inside view:

 
Thanks!
 

Saw your question before about the roof screws and I did not answer as I only used the painter or coated roof screw tops you are talking about.
I have found it very difficult to get good rust proof or quality ss screws here. I think those coated roof screws with the rubber under the screw head and the drill bit at the end are fine, but try and buy the most expensive ones. I have no real technical knowledge on this, just what I did.
About the silicon or filler around the bird windows, I saw in another thread someone recommend the product No More Nails. I haven't used it and I always try and buy 100% silicon or the most expensive one in the range.

If you haven't bought some bird stop windows that match your tiles, you need to get some and see if it will fit around those valleys under the tiles. Sorry not much specific help.

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[simoh1490]

I can't help with the screws I'm afraid, I simply don't know, sorry!

 

The gap: If the gap can be accessed from the inside of the roof I'd be inclined to cut a length of thin sheet metal and overlay/cover the gap and tack it in place with rivets. It only needs to be say six inches wide and you can buy rolls of galvanised steel (looks like tin) very inexpensively. The problem with silicone or similar is that you're trying to seal a gap between two metal surfaces, both of which are exposed to direct sun and both of which expand and contract at different rates, the seal is therefore not likely to last a long time. Rivets are cheap, quick and effective, a rivet gun will cost maybe 150 baht and a bag of rivets about 50 baht.

[carlyai]

I can't help with the screws I'm afraid, I simply don't know, sorry!
 
The gap: If the gap can be accessed from the inside of the roof I'd be inclined to cut a length of thin sheet metal and overlay/cover the gap and tack it in place with rivets. It only needs to be say six inches wide and you can buy rolls of galvanised steel (looks like tin) very inexpensively. The problem with silicone or similar is that you're trying to seal a gap between two metal surfaces, both of which are exposed to direct sun and both of which expand and contract at different rates, the seal is therefore not likely to last a long time. Rivets are cheap, quick and effective, a rivet gun will cost maybe 150 baht and a bag of rivets about 50 baht.

Yes good idea simoh1490. I did the same with some metal roofing, where the veranda tiles meet the roof trusses tiles. It was bent at 90 degrees and the top bit cut to the waved shape of the tiles and the bottom flat bit shaped over the tiles. I used those screws for the top bit and siliconed the bottom bit as it was sticking up a bit and would not lay properly on the tiles. It has worked well with no prob. but only 4 years.




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[carlyai]

Yes good idea simoh1490. I did the same with some metal roofing, where the veranda tiles meet the roof trusses tiles. It was bent at 90 degrees and the top bit cut to the waved shape of the tiles and the bottom flat bit shaped over the tiles. I used those screws for the top bit and siliconed the bottom bit as it was sticking up a bit and would not lay properly on the tiles. It has worked well with no prob. but only 4 years.




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Here's some pics.I just took.

1. Have the metal roofing cut to size screwed on and siliconed underneath. Between the roof and veranda tiles.

2. Valley drain.

3. Stop bird windows on the veranda.


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[simoh1490]

Yes, nice job plus it looks good, the bad guys will never get in that way!

[Kwasaki]

15 hours ago, Sheryl said:

Something to worry about or not? The screws available have the rubber washer at the head and are copper coated (or coated with something of copper color). ??

There OK got my first ones for roof repairs 10 years ago no problem.

Fixed top of roll if using roof sheets is better practice.

 

15 hours ago, Sheryl said:

roof of the valley gutters,

Been answered in many post pix and post descriptions already.

[simoh1490]

An easier solution to the sealant/gap issue might be to use wire netting (only on the inside of the roof) to seal the gap and prevent ingress by wildlife, as long as you use wire netting with small holes in it, it will stand the test of time and since it's in the roof space, who cares what it looks like.

[wayned]

Another option, maybe!  Somewhere recently in this 32 page discussion, Sheryl said that she had bought "eaves filler pieces" that match the contour of the roof.  I don't know what they look like, but you might be able to use them inside and fit them between the flashing and the roofing and secure them with screws through the flashing!

[simoh1490]

4 minutes ago, wayned said:

Another option, maybe!  Somewhere recently in this 32 page discussion, Sheryl said that she had bought "eaves filler pieces" that match the contour of the roof.  I don't know what they look like, but you might be able to use them inside and fit them between the flashing and the roofing and secure them with screws through the flashing!

I agree. In fact there's a number of possible ways to do this, all of which are good, the only way that is probably not so good is to use sealant. 

[Sheryl]

Thanks, all. I am a little unclear -- up all night helping my niece with  some very complicated statistics for her master's thesis, so my brain is a more than bit scrambled... 

 

In Simoh's suggestion post 473, I would affix a strip of metal sheet over the place where the rims of the valley gutter meet the tiles, from inside the roof, is that right?  What is the advantage of this over just affixing the edges of the valley gutter to the tiles? Either way it involves affixing metal to tiles??

And how exactly do I affix? You mention rivets, are they appropriate for affixing metal to tiles? elsewhere Wyaned mentioned screws?

 

In Wayned's post 479, suggesting to use the eaves filler, I had thought of that too but am not clear  (1)  how I would fasten it to the valley gutters (screws? rivets?) and (2) whether doing this would create opportunity for small water seepage around the screws or rivet holes, since I would have to put those through the rims (lips) of the valley gutter to affix it to the eaves filler?

 

[simoh1490]

11 minutes ago, Sheryl said:

Thanks, all. I am a little unclear -- up all night helping my niece with  some very complicated statistics for her master's thesis, so my brain is a more than bit scrambled... 

 

In Simoh's suggestion post 473, I would affix a strip of metal sheet over the place where the rims of the valley gutter meet the tiles, from inside the roof, is that right?  What is the advantage of this over just affixing the edges of the valley gutter to the tiles? Either way it involves affixing metal to tiles??

And how exactly do I affix? You mention rivets, are they appropriate for affixing metal to tiles? elsewhere Wyaned mentioned screws?

 

In Wayned's post 479, suggesting to use the eaves filler, I had thought of that too but am not clear  (1)  how I would fasten it to the valley gutters (screws? rivets?) and (2) whether doing this would create opportunity for small water seepage around the screws or rivet holes, since I would have to put those through the rims (lips) of the valley gutter to affix it to the eaves filler?

 

In your post 467 above you ask the question about sealant and show pictures of the area that requires sealed, my posts are in the context of those pictures. BUT, you're now talking about tiles, did I miss something whilst I was away, it sounds as though you changed your roofing material?

 

Regardless, if you did so, then you still have a gap between two surfaces that need to be filled, except one is now tile and the other is metal. Those things being true the same issue of heat and expansion remains and a mechanical solution rather than a chemical one would be better, the variable will be what material to use (small cell wire netting or sheet steel/alloy) and how it is fastened and held in place.  If it was me I would pass this one to the roofers and tell them you want that gap closed and why but not to use sealant, then offer them the choice of netting or metal sheet - they will find a way to fasten it, which without actually seeing it first hand, is hard to imagine and describe. 

 

Also, sheet metal rivets and sheet metal screws, don't offer much opportunity for water ingress, if truly concerned by this aspect, put a small "glob" of sealant on the rivet or screw head but it's no necessary.

Edited November 20, 2017 by simoh1490

[carlyai]

In your post 467 above you ask the question about sealant and show pictures of the area that requires sealed, my posts are in the context of those pictures. BUT, you're now talking about tiles, did I miss something whilst I was away, it sounds as though you changed your roofing material?
 
Regardless, if you did so, then you still have a gap between two surfaces that need to be filled, except one is now tile and the other is metal. Those things being true the same issue of heat and expansion remains and a mechanical solution rather than a chemical one would be better, the variable will be what material to use (small cell wire netting or sheet steel/alloy) and how it is fastened and held in place.  If it was me I would pass this one to the roofers and tell them you want that gap closed and why but not to use sealant, then offer them the choice of netting or metal sheet - they will find a way to fasten it, which without actually seeing it first hand, is hard to imagine and describe. 
 
Also, sheet metal rivets and sheet metal screws, don't offer much opportunity for water ingress, if truly concerned by this aspect, put a small "glob" of sealant on the rivet or screw head but it's no necessary.

Hi simoh1490, yeah the metal roof mob let her down, so she went back to the newer style old tiles. I think fibrocement like before.
I can't see how you successfully screw the metal to the fibrocement or non metal tiles without using some sealant. The builders will probably know, as you say.

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[simoh1490]

9 minutes ago, carlyai said:

Hi simoh1490, yeah the metal roof mob let her down, so she went back to the newer style old tiles. I think fibrocement like before.
I can't see how you successfully screw the metal to the fibrocement or non metal tiles without using some sealant. The builders will probably know, as you say.

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Ah, I must have missed that part! Thanks.

 

I think it's the same answer, let the roofing guys sort it.

[simoh1490]

On 17/11/2017 at 12:48 PM, carlyai said:

Hello Simoh1490,

Why would you not expect the attic temperature to be reduced with the new white roof?

If the temperature is not reduced with the white roof, why install a white roof? Would any color have done?

Not questioning you, just I don't know.

Also are you saying because of the different cooling factors that come into play in keeping the bottom foot of the attic cool, it is better to have a large attic space rather than a small attic space; even though with a large attic space you will have more air to get hot?

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Sorry but I missed this post whilst I was away........I think it probably came as a result of me saying the following earlier, "I would not expect your attic temperatures to be reduced as a result of your new roof, cooling the attic is NOT your objective and none of the things you are doing will achieve that".

 

The colour of the roof is important in that light colours reflect heat whilst dark colours absorb it. Take two wet shirts and hang them in the sun to dry, one dark and one white, the dark shirt will always dry much more quickly than the white shirt. BUT, both shirts will eventually dry hence the choice of colour only delays heat transfer rather than negate it entirely. The same is true of domestic roof insulation which merely slows down the transfer of heat rather than eliminate it completely.

 

The other factor to consider is that, regardless of the speed with which heat transfers to the roof (regardless of colour) there is another transfer that takes place and that is from the roof surface to the steel rafters and that is conductive heat which is less influenced by colour - the steel rafters then become the source of heat in the attic which then heats the air.

 

So if you have two roofs, one black and one white, I would expect to see the air in the attic space under the darker coloured roof, heat up much sooner and maybe reach a slightly higher temperature later in the day (I'm not entirely certain on this point but I believe not) - the air under the lighter coloured roof would remain cooler for longer but would eventually reach a very similar temperature level to the darker roof, albeit later in the day. The practical application of the above is that a lighter coloured roof buys you more time throughout the day before the insulation becomes the first line of defence against heat penetration into the living space.

 

As for size of attic/roof space: I don't know is the short answer!  A longer answer suspects it might have something to do with the surface area of radiated heat from the roof and its proximity to the ceiling of the living space/insulation. I'm pretty sure however that as long as the amount of ventilation in a roof space is proportionate to the volume of that roof space (and there are calculators available to help you understand what this volume measurement should be)  the size of the roof void shouldn't be an issue.