gyp questions

Plumdog_2

when I read "poor performance" and "cracks". I thought you were Gypcrete fan from day one!

Terry Larsell

gypcret questions

Looking to do my first gypcrete job. Homeowner/builder is lining up the gyp. Gyp installer is recommending a base sheet that is pricey. Homeowner is talking 6 mil poly. I always thought that gyp was supposed to bond to the plywood and that you use some sort of paint on coating to prep the floor.

Homeowner also has been reading about bonding issues for tile and is having second thoughts.

Anyone experienced with these issues I would love to hear from you.

Terry

[Deleted User]

Gyp versus light weight cement...

Gypcrete is usually prepped with a bonding agent that is sprayed onto the wood just before application. You're corrext in your assesment that gyp is supposed to be bonded to the wood.

Lightweight cement HAS to have a bond breaker sheet applied prior to application of the cement. It is the EXACT opposite of gyp.

As for bonding tile to gypcrete, or lightweight cement for that matter, it is strongly recommended that a crack isolation shield be applied directly to the top of the gyp to allow tile to properly adhese. Attempting to put tile directly on the gyp will result in massive tile failure and dis-satisfied consumer.

There is a sealant called Hydroment, which is a silcone based (STINKS) sealant that can be used in lieu of a plastic crack isolation shield. It too must be trowled onto the floor evenly and allowed to cure prior to bondiing tile.

Have you looked at WarmBoard yet?


www.warmboard.com

Although the outward appearance is that the WB is MUCH more expensive than gypcrete, once everything, and I do mean EVERYTHING is taken into consideration (stronger tji's for the 14 # per square ft dead load, second sole plate, cost of gyp, poor performance of gyp, crack iso shields etc) the WB is NOT that much more expensive, and the thermal performance over gypcrete is incomparable. THe WB can operate with temps in the range of 100 degrees F, whereas the gyp may require temps as high as 140 to accomplish the same thing.

WB is a REQUIREMENT on all of our high efficiency (ground source heat pump, solar, condensing boiler) applications.

Think outside the gypcrete box...

ME

Terry Larsell

warmboard

I am doing a warmboard at this time. The tubing is in and I am waiting for the framers to dry it in. It is expensive but it was easy to tube, I'm anxious to see how it works. A lot of rain lately has the seams swelling quite a bit, I'm hoping once it dries out that it settles down a little, the belt sander does not seem to be an option with warmboard.

This gyp job is to cut up and far along for warmboard, I am looking at thermofin and plywood as another option. I have had success with plates and tube but the labor involved is not something I look forward to.

Terry

[Deleted User]

I was...until we started doing GSHPs.

> when I read "poor performance" and "cracks". I

> thought you were Gypcrete fan from day one!



Then gyp became an issue. It CAN still work, but WB is SO much easier, and faster.

ME

[Deleted User]

I was....

until we started doing GSHPs

Then gyp became an issue. It CAN still work, but WB is SO much easier, and faster and SO much more efficient.

ME

jp_2

WB and tile

It seems to me that cbu transfers heat rather poorly?
not as good as gyp.

how do you handle all the air pockets between WB, tubing and the cbu? thinset? are you using 1/2 inch cbu?

jim

Troy_3

WOW I disagree

We have never installed Warmboard. I've been called in twice to try to fix warmboard noise problems installed by others. I am a RapidFloor gypsum concrete applicator so I know you will think I'm biased. I just can't get by the benefits of gypsum concrete mass. It is silent. It also makes the house quiet between rooms and between floors. We have 2 gshp jobs we are installing now and we won't do them without gyp. Pouring gyp is not fun if there was a method of radiant that I found to equal gyp. I would sell my pump in a second.

Troy_3

Gypsum concrete

back to the original question- I agree with Mark that the gyp gets a bonding agent sprayed to the subfloor before it is applied. What brand of Gypsum concrete? Check with the manufacturer. It will spell out the procedure in the specs of the product. They all have web sites. Make sure the tube is stapled down so it doesn't bounce or move.

Plumdog_2

Thanks

for getting back. What's involved in becoming a Gyp applicator? It seems sort of like a Dealership arrangement or something. Can a hillbilly buy a pump and instructions and materials and have a go on a small scale or would it be too risky?

[Deleted User]

Spoken...

like a true gypcrete dealer Troy. If I were in your shoes, I'd probably take the same stance. As for advantage of mass, mass will KILL you if you have a solar gain situation.. NO?

WB, being relatively massless reacts much quicker to compounded gain situations.

In a properly designed, properly installed, operated and controlled WB system, there are no equals.

And THAT is MY obviously biased opinion, and I don't make a large profit off of their product. But then again, I make ZERO profit off the gyp jobs. Occasionally a pair of hockey tickets, but that's it.

To each is own.

ME

Troy_3

Gypsum concrete applicator

I think if you have a spare 100K you probably can talk one of the manufacturers into setting you up. It is really a whole new business. It's tough surviving just pouring radiant jobs. The bagged material comes palletized 50-80# bags to a pallet. 12 pallets to a truck. If you can find a local appicator that will work with you I think it really is easier tolet them handle the pour. JMHO

jp_2

geeze mark?

""mass will KILL you if you have a solar gain situation.. NO?""

I would think solar & mass would work FOR you. why not use free energy? its not nuclear science.

jim

Unknown

If the mass is already heated, and gets hit with the solar gain, the occupants will open their windows. There goes all that free heat.....

This can be mitigated, but ultimately speaking, using passive solar with high mass radiant depends on there being occupants either gone during the initial gain event, or willing to sweat it out for a few hours.

also, use PEX-AL-PEX in warmboard. all those noise issues go away quite nicely. good controls help too.

jp_2

poor design, poor performance

sure I agree, anything designed poorly will not work right.

so, zoning solar areas separate , adding a tsat to sense over heating or 'rate of heating' will not work?

seems to me ANY heating system within a high solar gain room and tile flooring will have the same overheating problems.

I think tile when hearing gyp

Unknown

Of course there are ways to handle it. Indoor feedback, slab sensing, etc. But the fact is, unless you can predict when the sun will be out and when it won't, that in some cases you have rapid solar gain for passive solar areas. Mass can only release its heat so fast. It is much more problematic than with a low mass system. Of course, then you lose storage capacity.

In that case, using the mass for storage and heating with a low mass application is ideal. Obviously with a big open floorplan that's not great if radiant floor is desired. But just now, for example, I am doing a radiant floor slab w/radiant ceiling. The slab provides a baseline heat, limited by floor temperature, and the ceiling does the rest, so it can back down quicker in response to high solar gain.

Free energy isn't too helpful if the occupants just dissipate it because it's too hot. Dealing with mass and solar gain just isn't as simple when the mass is your primary heat. I'm not trying to say that one should never use slab radiant where solar gain is a concern... I'm just saying it's definitely simpler to use a low mass form of radiant in those cases.