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A month ago I poured 1 1/2 inches of gypcrete over plastic tubing, stapled to a 3/4 inch plywood subfloor.
The floor has been warm for the month.
The gypcrete developed hairline cracks, in line with the tubing (more or less).
It still cracks— or at least sounds like it!
To owners of gypcrete floors— to they continue to POP!!?– and for how long!?
Thanks very much,
Rick
Prescriptive codes don't address the connection at less common angles, so base the connection off more typical ones using bolts, structural screws, blocking, and steel tension ties.
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Replies
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A month ago I poured 1 1/2 inches of gypcrete over plastic tubing, stapled to a 3/4 inch plywood subfloor.
The floor has been warm for the month.
The gypcrete developed hairline cracks, in line with the tubing (more or less).
It still cracks--- or at least sounds like it!
To owners of gypcrete floors--- to they continue to POP!!?-- and for how long!?
Thanks very much,
Rick
*What does Gyp-Crete have to say about it? If possible could you outline the conditions between pour and startup of the floors ie: ambient air temperature, water temperature, time between placement of Gyp-Crete and startup of floorheat, etc.
*What does Gyp-Crete have to say about it? If possible could you outline the conditions between pour and startup of the floors ie: ambient air temperature, water temperature, time between placement of Gyp-Crete and startup of floorheat, etc.
*Rick,As I mentioned to Nick (see Breaktime message below yours) my Gypcrete floor have not shown any signs of cracking after 5 heating seasons. I waited a month or more before heating the slab (1 1/4") and raised the temperature slowly as recommended. Delivery water temperatures in my system do not exceed 95 F. Essentially, this re-iterates what Jeff said.
*Here is the history----The addition has been standing for about 3 years. Had been heated for that time via the bottom, subgrade level. (Radiant heat in a conventional 4 IN concrete slab).Was finally time to pour the gypcrete in the main level! Gypcrete was poured and heat supplied. Was too hot! As hot as 145 degrees! Started developing cracks. Gypcrete contractor said some hairline cracks were normal but when he heard the temp, he said shut off heat until it gets fixed.Turned out that the mixing value design on the boiler was bad design, from the get go--- too much hot boiler water was always being supplied, no matter what the setting on the mixing valve. Apparently the conventional concrete slab didn't mind (for 3 years), but the gypcrete did! Couldn't get the system redesigned for about 3 weeks so I turned the boiler way down-- to about 100 or 110 degrees!Finally I found a good radiant guy and he redesigned the mixing valve circuit. Now it works great.Popping occurs sporadically but mainly if I try to use my set back thermostats--- when the warm water floods in, is when popping can be counted on!Also the room trampolines a bit, which I'm sure doesn't help!So---- A post mortem--- too much heat and a slightly bouncy room result in cracks and pops??!!-- Regards,RickPS---- could I have asked for a gypcrete mix that was more flexible?
*Alex---You saind in your post-- "Essentially, this re-iterates what Jeff said. "I cant find what Jeff said! Can you please help?Thx,Rick
*If you think you have problems now wait about 15 to 30 years when the pipes start cracking or getting clogged with minerals.
*Hi Rick,Essentially, Jeff was asking you about the conditions during the Gypcrete pour and during the slab curing. I think you have yourself provided an explaination for the cracking - applying too much heat too soon after the pour. My guess is that the heat supplied exceeded normal curing requirements for the Gypcrete and voids formed around the tubing. Any floor movement will be amplified by the voids.
*Bob,Could you support your suggestion with some case histories?Alex
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were the lines pressurized while the gypcrete was being poured? This is vitally important because the PEX and TPR hoses will expand significantly. This creates tensile stress in the gypcrete. Since gypcrete and concrete have no tensile strength they crack. Spongy floors aren't helping the situation either. I suspect the popping sound is the tubing slipping back and forth within the now loose channels in the slab.
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Sorry,I cannot support my fears with any case histories until about another 10/20 more years as the use of this type of system is relatively new. I have seen plenty of evidence of mineral clogging in domestic hot water pipes during remodels however and I am just wondering I guess what will make hydronic radiant systems immune to this. Also there have been some tubing companies blacklisted by the local plumbers after they were used exclusively for awhile, why is that? I especially want to point out the scenario described by Rob Susz above. Won't the pipes if allowed to expand/contract, which you know they are going to do due to the heat/cool of the piping,eventually wear through from contact with the concrete/gypsum matrix? How many lifecycles of expansion/contraction are these products tested for?
I am probably all wrong here in most peoples eyes but hey, this is America right, you know, freedom of expression and all that. I for one will stick with other methods of heating but my biggest concern personally is an efficient building envelope that does not need alot of mechanical assistance to heat/cool.
*Hi Bob,Hydronic systems have a fairly long history in Europe where the Romans first applied the principle of heated floors. There is at least a couple of decades of data on plastic systems. Radiant floors, unlike domestic water supplies, are essentially immune from mineralization because they are closed systems i.e. the water is not continuously replaced. I have had the same water in my system now for 6 years and there are no signs of mineralization or serious corrosion. I didn't add antifreeze or corrosion inhibitors when I initially filled the system with water. Following correct installation procedures for all system components including Gypcrete pours will generally ensure an efficient, smoothly operating system that is no more complicated than a forced air system.
*Yes---The plastic pipes were pressurized to about 30 or 40 PSI.Also-- Bob brings up a point about expansion/contraction--- which I quote--- " Won't the pipes if allowed to expand/contract, which you know they are going to do due to the heat/cool of the piping,eventually wear through from contact with the concrete/gypsum matrix? How many lifecycles of expansion/contraction are these products tested for? "So, maybe I 'screwed up in reverse' , by giving the pipes a little extra elboe room to expand in!!!Later,Rick
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A month ago I poured 1 1/2 inches of gypcrete over plastic tubing, stapled to a 3/4 inch plywood subfloor.
The floor has been warm for the month.
The gypcrete developed hairline cracks, in line with the tubing (more or less).
It still cracks--- or at least sounds like it!
To owners of gypcrete floors--- to they continue to POP!!?-- and for how long!?
Thanks very much,
Rick