Roger R
Basic Member
Posts:131
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| 21 Jul 2013 03:35 PM |
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We are building on an island in Northern Washington State and there is a Navy jet test base a couple islands south. The noise can be annoying at times and loud if they fly overhead. I have studied SIP roofs, and for insulation they seem great - but for sound, they seem lacking. Is possible to pour a concrete angled roof?
How would we do this, what type of forms, how thick should the concrete be, any special slump, what keeps it in place (so it doesn't run off the pitch of the roof while setting up) and how would we insulate it? If we hung joists and filled with fiberglass, would we vent the concrete like we would a wood roof?
Any advice and comments are welcomed. Thanks. |
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jonr
Senior Member
Posts:5341
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| 21 Jul 2013 03:57 PM |
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One option is Insul-Deck (~STC 50). But you can achieve higher STC ratings from more conventional roofs + acoustic enhancements. Also make sure that you do a balanced design where windows and walls are considered.  |
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Lbear
Veteran Member
Posts:2740
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| 21 Jul 2013 04:19 PM |
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Posted By Roger R on 21 Jul 2013 03:35 PM
We are building on an island in Northern Washington State and there is a Navy jet test base a couple islands south. The noise can be annoying at times and loud if they fly overhead. I have studied SIP roofs, and for insulation they seem great - but for sound, they seem lacking. Is possible to pour a concrete angled roof?
How would we do this, what type of forms, how thick should the concrete be, any special slump, what keeps it in place (so it doesn't run off the pitch of the roof while setting up) and how would we insulate it? If we hung joists and filled with fiberglass, would we vent the concrete like we would a wood roof?
Any advice and comments are welcomed. Thanks.
Concrete roofing is very $$$ expensive. You are looking at $25-$30 per square foot once all is said and done. So if your roof is 2,500 sqft of surface area, get ready for a $63k - $75k bill. Unless you are getting a concrete roof for DISASTER resistance issues (tornado, hurricane, etc), I would not recommend a concrete roof based solely on noise suppression. You would still have to decouple the concrete roof on the inside with furring channels as you would with SIPs. Plus you still have to waterproof and finish the outside concrete roof with a roofing material. If sound isolation is what you are after, and you don't want to do SIPs with decoupled furring channels. The option is simple. Just get a wood truss attic, blast in 20" of cellulose, hang 5/8" drywall and call it a day. You will be around STC 55+ when all is said and done. It's the cheapest option out there. The truss attic gives you an air space between the outside and the cellulose acts like a sound deadening material in addition to giving you a high R-Value. Of course a truss attic with 20" of cellulose will not work if have cathedral ceilings or some other non-standard roof design. |
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Alton
Veteran Member
Posts:2164
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| 21 Jul 2013 05:34 PM |
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Roofs can be made with placed concrete. Steep pitches will require a stiff mix. I would not try to exceed 6 to 12 pitch with placed concrete. However, much steeper roofs can be done with gunite or shotcrete. Precast concrete panels (with or without insulation) have been used for up to 6 to 12 pitch. Availability in your area will affect prices. |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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Roger R
Basic Member
Posts:131
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| 22 Jul 2013 03:09 PM |
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Posted By Lbear on 21 Jul 2013 04:19 PM
If sound isolation is what you are after, and you don't want to do SIPs with decoupled furring channels. The option is simple. Just get a wood truss attic, blast in 20" of cellulose, hang 5/8" drywall and call it a day. You will be around STC 55+ when all is said and done. It's the cheapest option out there. The truss attic gives you an air space between the outside and the cellulose acts like a sound deadening material in addition to giving you a high R-Value.
Lbear,
Concrete roof sounds too expensive. Are there STC charts out there that can verify what you mentioned about 5/8" sheetrock, 20" of insulation and an STC of 55+? That rating sounds awfully high (large) to me. |
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Lbear
Veteran Member
Posts:2740
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| 22 Jul 2013 05:41 PM |
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Posted By Roger R on 22 Jul 2013 03:09 PM
Lbear,
Concrete roof sounds too expensive. Are there STC charts out there that can verify what you mentioned about 5/8" sheetrock, 20" of insulation and an STC of 55+? That rating sounds awfully high (large) to me.
If you decouple the ceiling with resilient hat channels, you are always going to gain a lot of sound proofing: STC RATINGSFor my house design I am going with a Steel SIP roof and the home is in a rural forested area. Even so, I will install resilient sound clips, furring hat channel, fiberglass batts, and 5/8" drywall to improve the STC Ratings. Plus I need a furring channel to run wiring. |
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theInvincible
New Member
Posts:74
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| 22 Jul 2013 05:47 PM |
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1 - Build a flat floor for roof.
2 - Install a simple stick wood roof on top of it.
There are lots of advantages.
1 - You can change it to flat roof in the future.
2 - You can build another floor in the future.
3 - It will be cool during summer. |
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QL
New Member
Posts:11
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| 23 Jul 2013 05:06 AM |
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Concrete roofs do not have to be expensive. Please contact Quad-Lock for an estimate. Hopefully the image below helps.  |
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jonr
Senior Member
Posts:5341
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| 23 Jul 2013 09:23 AM |
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QL, what is the least expensive roofing that can be used over the concrete? Is the top surface of the concrete crack free enough that nothing could be used? |
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Lbear
Veteran Member
Posts:2740
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| 23 Jul 2013 04:01 PM |
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Posted By QL on 23 Jul 2013 05:06 AM
Concrete roofs do not have to be expensive. Please contact Quad-Lock for an estimate.
Unfortunately they are expensive, that's the reality of it. I called around and nobody came in under $25 per sqft and these were experienced crews who have completed such roofs in the past. Most crews were located on the east coast but still nobody came in under $25 sqft and it went up in price from there. If the average ICF wall is going for $15+ per sqft (wall space) today and InsulDeck/QuadDeck for a floor is going for around $19 per sqft, how is a pitched roof going to come in less than any of those two prices? |
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QL
New Member
Posts:11
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| 24 Jul 2013 01:22 PM |
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jonr - concrete will crack - no matter what - especially on roofs being exposed to hi-low temperature cycling - however you can prevent this by adding fiber reinforcement to your mix. Together with waterproofing additive and a sealant this was proven to work on green roofs. No membranes. You would have to run your numbers to see if it's more cost effective than placing on a membrane with furring and tiles. Lbear - I respect your opinion and I am sure it is true. However, from experience I can tell you that 19 and 25 are really really high numbers. This really comes down to doing the math on Quad-Deck, concrete, rebar, shoring, engineering and labor and finishes. I am sure the folks at Quad-Lock can give you all of this. cheerio  |
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d'techguy
New Member
Posts:35
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| 24 Jul 2013 03:59 PM |
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There seems to be a very wide range of pricing for ICF roof structures. However, anything past the first $12 or so is labor. If you want to pay for someone to learn on your job, that is up to you. I recommend finding a crew with experience to keep the cost down and the quality up.
Lbear nailed it when he said that concrete roofs carry a premium. I suggest that you need to have a compelling reason to consider this option, of which there are many: Disaster resistance, fire resistance, and long-term durability are just for starters. The ability to use a flat roof for living space or agriculture is another big one.
QL hit on an important point, but didn't expand: There are additives that will make concrete water-tight. KRYTON puts out a product called KIM (Kristol Internal Membrane) that is excellent, and made in the NW. www.kryton.com Xypex is another name that has been around a long time.
Cheers,
DJB |
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sharter
New Member
Posts:77
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| 25 Jul 2013 09:33 PM |
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Don't rule out (mostly) flat roofs. The "warm" design where membrane is against the concrete and insulation is put on top is the newest and best design, and should last for many, many years. The ability to have green space or a view is the clincher. |
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d'techguy
New Member
Posts:35
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| 26 Jul 2013 10:43 AM |
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One way to keep the cost of a concrete T-beam floor or roof (flat or pitched) down is to 'Value-engineer" the structure. This means optimizing the structure by cutting down the spans wherever possible....i.e.: place intermediate beams to carry the loads to the supporting structure. For example, if one has a 30 foot span, a beam can be placed at center of span to cut it into two 15 ft. spans. This will yield a much lighter and inexpensive floor/roof structure.
One would have to weigh the cost of the beam versus the savings in the rest of the structure, but many times this works well. The intermediate beam can be concrete or steel, and may be contained within the cross-section of the floor, or with very little reveal on the underside.
d |
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jonr
Senior Member
Posts:5341
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| 26 Jul 2013 11:00 AM |
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The intermediate beam can be concrete or steel, and may be contained within the cross-section of the floor, or with very little reveal on the underside. Or it could be a concrete interior wall. But some combination of multiple layers of drywall, Green Glue, resilient channels, fiberglass+cellulose loose fill insulation, Roxul Comfort/Mono board and steel trusses/joists will do better from a sound standpoint. |
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irnivek
Basic Member
Posts:229
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| 29 Jul 2013 05:23 PM |
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We like our Hambro roofs with spray foam underneath and have also used Litedeck, Amdeck, Insuldeck etc.
But I wouldn't go concrete to solve noise transmission if that is you main goal. As stated, cheaper other ways to get a quite structure. |
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Roger R
Basic Member
Posts:131
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| 29 Jul 2013 06:16 PM |
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Posted By irnivek on 29 Jul 2013 05:23 PM
We like our Hambro roofs with spray foam underneath and have also used Litedeck, Amdeck, Insuldeck etc.
But I wouldn't go concrete to solve noise transmission if that is you main goal. As stated, cheaper other ways to get a quite structure.
Cheaper is better. Can you please give me some specifics how to build a roof that will be insulated against heat/cold and keep out the sound of fighter jets that fly overhead occasionally? |
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ICFHybrid
Veteran Member
Posts:3039
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| 30 Jul 2013 09:28 AM |
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keep out the sound of fighter jets that fly overhead occasionally You are not going to find something to keep out the sound of an EA-18 "Growler" flying low and slow, except maybe a bunker. I heartily recommend Insulated Concrete Form construction to help some with that, but I wouldn't obsess about the roof. Which island are you on? You will need a contractor because my personal opinion is that an ICF roof is beyond what amateurs should attempt. I can give you the name of the contractor who can pull that off. |
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Roger R
Basic Member
Posts:131
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| 30 Jul 2013 01:39 PM |
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Posted By ICFHybrid on 30 Jul 2013 09:28 AM
Which island are you on? You will need a contractor because my personal opinion is that an ICF roof is beyond what amateurs should attempt. I can give you the name of the contractor who can pull that off.
ICF,
Please PM me the contractor's name and info. Thanks. |
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jeff m
New Member
Posts:1
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| 03 Aug 2013 05:50 PM |
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1. Will waterproofing additives (like Hycrete, Xypex and Krystol) work for waterproofing a ICF deck used as a roof? I'd like to do that, with a ClearSpan fabric 'roof' (think fabric farm building) over an ICF deck to provide shade & to direct rain/snow runoff. My thinking is if I want to add a 2nd floor later I can leave rebar exposed on the original pour (which I would have used to anchor the fabric roof frame, take the fabric roof off, add another ICF wall & deck and then put the fabric roof back on (or add a green roof).
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