recessed lights and SIPS
Last Post 04 Mar 2009 01:03 PM by Alton. 37 Replies.
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David BUser is Offline
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19 Jun 2008 10:04 PM

Hello all,

I have been reading this forum for months and thanks for all the information.  Now for my question.

I am planning a new home in Southern Louisiana to be built with OSB SIPS.  I wanted to use SIPS for the exterior walls and roof but found the cost prohibitive due to the complex roof.  My answer is to use SIPS for the exterior walls (6.5") and ceiling (8.25").  Conventionaly framed vented roof is to cover the entire structure.  My question is, how to install recessed lighting in the celing panels without 1) damaging the structural integerity of the  ceiling 2) elemilating the thermal barrier in the ceiling when installing the lighting cans?

Thanks in advance!



wesUser is Offline
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20 Jun 2008 08:29 PM
If your roof is that complex, I would suggest spray foam (Icynene, etc.) on the underside of your roof decking.
It creates an insulated attic space for your duct work (if any), and allows the use of conventional can lites as you wish.
I would never install can lites in a SIP ceiling assembly. Too many variables to sealing and insulating around the lites.


Wes Shelby
Design Systems Group
Murray KY
wandr@ainweb.net
David BUser is Offline
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22 Jun 2008 10:17 AM
OK I understand that recessed lights are a bad idea with SIPs. Luckily we are planning 10' ceilings and have some room to build a tray ceiling in which we can install the lights, 10' in the center and ~ 9' at the sides of the room. Does anyone have experience with hanging this type of load from a SIP ceiling?

As for insulating the roof with spray foam, it is very unclear to me if an invented attic is a good idea in out humid climate. Asphalt shingle warranties are likely compromised and humidity buildup in this space are major concerns of mine.


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22 Jun 2008 10:53 AM
Posted By David B on 06/22/2008 10:17 AM
, it is very unclear to me if an invented attic is a good idea in out humid climate.
Asphalt shingle warranties are likely compromised and humidity buildup in this space are major concerns of mine.
David;

the absolute best way to build in a hot humid climate is with an unvented attic.

Shingle life WILL be diminished by about 10%

There are recessed cans desined to be used surrounded by insulation and I would not hesitate to use one in our SIP panels, as long as there was sufficent depth for the can.

Structural integrity is not compromised in the panels with a skylight, let alone a little can.



Chris Kavala
info@southernsips dot com
1-877-321-SIPS
FL. Lic # CBC036455, GA Lic. RLCO000624, LA Lic. # CL33845
The Panel GuyUser is Offline
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22 Jun 2008 12:08 PM
Recessed lights in SIPs, a bad idea.................. oh contra ! It is true that an 8 1/4 inch panel is not the ideal thickness for a recessed light, but being the creative beings that we are, we have found ways to even make that work. A 12 1/4 inch panel is the thickness of panel to use if you want your can lights to be flush mounted. With both an 8 1/4 and 10 1/4 inch panel we came up with an pleasing detail where we do a build out so the
recessed can is partially in and partially out of the panel. Our first experiment turned out to be a very pleasing finish detail.

The issue with recessed cans in SIP panels is due to the heat build up by the fixture itself. Even those cans that are made so that insulation does not have to be pulled back will have heat buildup. After doing our homework on this issue, we found that the biggest concern is allowing additional heat into the recessed can cavity from external sources, causing the heat sensor to shut the light down. The heat sensors in recessed can lights trigger at 1/2 the amount of heat that causes concerns about heat buildup melting the foam in the SIP panel.

Cutting a recessed can (approximate depth of 8 inches ) into a 12 1/4 inch panel, will leave 3 to 4 inches of foam as a barrier to block heat from the exterior surface to penetrate into the recessed can cavity. In our test house that our clients have been actually living in for two years now, with a 12 1/4 inch roof, they have never had a can light shut down. Thing is they don't turn their lights on until it gets dark, when the heat of the day has passed and in the shorter winter mornings it's cold outside so no heat issue again.

We have two new test houses, one with a 10 1/4 inch panel and one with an 8 1/4. In the 10 1/4 inch panel we built a 2 inch furring ring around the can location and mounted the can housing to it. Point was to maintain the 3 to 4 inches of foam between the can and the exterior surface of the panel. We just installed finishes on the 8 1/4 inch roof where we built out a double stepped ring with 4 inches of depth, which has a very architecturally pleasing look to it, once again maintaining the solid foam between the cavity and the exterior surface.

I was glad to see that David B was not abandoning the use of SIPs for his roof structure by considering to still use them at his ceilings. As SIPs are becoming more popular, the thinking caps are lighting up (little segway into the subject matter) and I've seen a couple of designs where the client had that type of cut up hip roof that really did not make sense to build it with SIPs and looked at using SIPs for their ceilings, installing the ceiling SIPs right over the top plates, adding a perimeter plate around the exterior of the building and installing his trusses right over the top. CHEESEHEADS - BRILLIANT ! I thought it was ingenious. They were still able to build a high performance energy envelope and still get the look of the roof that was designed. One of the designs also had the ceiling SIPs installed inside the exterior plate lines with the exterior walls running above the SIP ceiling 3 inches minimum. That was a Southwest design and the band they ran around the perimeter to carry the SIP ceiling was also an architectural detail.

In the case of installing can lights in a flat ceiling, simply cut out a square hole and pop in your can light. To maintain the integrity where the hole was cut, build a box (out of SIP scrap cutouts) to install over the top of the can in the attic space. Make it big enough to give the can some breathing room, you could even poke some small holes (using those small round vent covers) to allow the heat from the can to dissipate into the attic like usual. Just an idea as I have not done this before, but I'm pretty sure it would work.

The Panel Guy


David BUser is Offline
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22 Jun 2008 01:16 PM
Much work has been done by LSU Agcenter on the design and building of a sustainable LA house. I am using this work to guide my decisions on building my LA house. You can view this information for yourself at .........
http://www.lsuagcenter.com/en/family_home/home/la_house/publications/Building+Your+Louisiana+House+A+Homeowners+Guide+to+Shaping+the+Future+for+Louisiana+Living.htm

Page 35 of 'Building Your LA House' states........
"If shingles are used for roofing, there should be a space with ridge and sofit vents for airflow between the insulation and roof deck to preserve shingle life."

Likely what I'll do is face the underside of the rafters with a foil backed radiant barrier with sofit and ridge vents. This will yield a semi conditioned attic space in which to install HVAC ducts. I'll use the idea of cutting a hole in the ceiling SIPs in which I'll install the desired recessed lights and top out the holes with a larger piece of scrap SIP material sealed to the top side of the ceiling SIPs. My goal is to have <$100.00 per month electric bills in this 3000 sq ft home once complete. We'll see!


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22 Jun 2008 01:57 PM
If a 30 year shingle roof installed on your house initially costs $7200 and the 10% loss of use would be $720.00 aver a span of 27 years,
It would take decades to re-coup the cost of a double vented roof to save $720.
Save the wood, save the trees and save thousands for the double roof deck


Chris Kavala
info@southernsips dot com
1-877-321-SIPS
FL. Lic # CBC036455, GA Lic. RLCO000624, LA Lic. # CL33845
PanelCraftersUser is Offline
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22 Jun 2008 05:23 PM
Posted By David B on 06/22/2008 1:16 PM
Likely what I'll do is face the underside of the rafters with a foil backed radiant barrier with sofit and ridge vents. This will yield a semi conditioned attic space in which to install HVAC ducts.

Or, you could chuck the radiant barrier, over insulate above the ceiling, and use a powered attic vent. They are available powered by PV, so no electricity costs. They do make a difference!


....jc
If you're not building with OSB SIPS(or ICF's), why are you building?
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22 Jun 2008 05:54 PM
Posted By PanelCrafters on 06/22/2008 5:23 PM
, and use a powered attic vent. They are available powered by PV, so no electricity costs. They do make a difference!
Powered attic vents are a bad idea in hot/humid climates they create negative pressure in the attic space,
sucking conditioned air out of the home and the duct system


Chris Kavala
info@southernsips dot com
1-877-321-SIPS
FL. Lic # CBC036455, GA Lic. RLCO000624, LA Lic. # CL33845
TFreidmanUser is Offline
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22 Jun 2008 06:27 PM
Lstibrurek addresses power vents , do's & don'ts in builders guide to SIPs 


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23 Jun 2008 06:47 AM
Posted By cmkavala on 06/22/2008 5:54 PM
Powered attic vents are a bad idea in hot/humid climates they create negative pressure in the attic space, sucking conditioned air out of the home and the duct system

Not if the attic has an ample supply of fresh air, and the living space is sealed. Hot/Humid, been there, done that.


....jc
If you're not building with OSB SIPS(or ICF's), why are you building?
cmkavalaUser is Offline
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23 Jun 2008 09:17 AM

Panelcrafters;

Facts.................. ducts leak, ceilings have penetrations,
vented soffits were major reason why homes sustained interior water damage during hurricane Charlie
as hurricane force winds blew water into attic space and saturated insulation/ drywall, quickly collapsed ceilings
to interior space, mold ensued quickly after no power to run dehumification & ACs. interior spaces were a total loss

Also not recognized as a good building practice by FSEC in hot and humid climates



Chris Kavala
info@southernsips dot com
1-877-321-SIPS
FL. Lic # CBC036455, GA Lic. RLCO000624, LA Lic. # CL33845
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23 Jun 2008 12:28 PM
Posted By cmkavala on 06/23/2008 9:17 AM

Panelcrafters;

Facts.................. ducts leak, ceilings have penetrations,
vented soffits were major reason why homes sustained interior water damage during hurricane Charlie
as hurricane force winds blew water into attic space and saturated insulation/ drywall, quickly collapsed ceilings
to interior space, mold ensued quickly after no power to run dehumification & ACs. interior spaces were a total loss


I was speaking 'in general'. Believe it or not, the world does not orbit Florida. And, if I was worried about hurricanes, I would build with steel reinforced concrete.

Also not recognized as a good building practice by FSEC in hot and humid climates

There's that Florida is the center of the universe stuff again. Building Sciences has designs for Hot & Humid climates that do use unconditioned attics.


....jc
If you're not building with OSB SIPS(or ICF's), why are you building?
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23 Jun 2008 01:00 PM
FYI............. FSEC services all of the US as far west as Wash. state


Chris Kavala
info@southernsips dot com
1-877-321-SIPS
FL. Lic # CBC036455, GA Lic. RLCO000624, LA Lic. # CL33845
GeorgiaTomUser is Offline
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23 Jun 2008 03:55 PM
Posted By PanelCrafters on 06/23/2008 12:28 PM

And, if I was worried about hurricanes, I would build with steel reinforced concrete.


PC;    are you still in the SIP business?


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23 Jun 2008 05:16 PM
Posted By GeorgiaTom on 06/23/2008 3:55 PM
PC;    are you still in the SIP business?

Yes. I don't believe in forcing a product into a situation. If I was worried about Hurricanes or Tornadoes, then I might build with ICF's. Of course, I could always build with SIPS and have a 'Safe Room'. Cost, is always another concern.

I am not close minded like some.


....jc
If you're not building with OSB SIPS(or ICF's), why are you building?
GeorgiaTomUser is Offline
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23 Jun 2008 05:25 PM

jc;

why wouldnt you build the safe room out of sips



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23 Jun 2008 05:32 PM
We are a distributor for Dupont Safe Rooms - which are made from sips with a layer of Kevlar for protection.


Roberta Bartel
Marketing Manager
Enercept - The Builders Choice
1-800-658-3303

Enercept Custom SIPS - Building today for a greener tomorrow.
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23 Jun 2008 06:28 PM
Posted By GeorgiaTom on 06/23/2008 5:25 PM

jc;

why wouldnt you build the safe room out of sips


Hmmm, I didn't say that I wouldn't! And, as Roberta stated, there are SIP safe rooms!


....jc
If you're not building with OSB SIPS(or ICF's), why are you building?
GeorgiaTomUser is Offline
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23 Jun 2008 07:08 PM
Hmmmm, ACTech does it with steel sips and they are allowed to get wet


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