Radiant Floor Gypcrete Framing Requirements

[cabinboy]

I have built my subfloor over a 4 foot crawlspace of CMUs using 2x10 16" o.c. The span of each joist is 12 feet supported by a center beam of 3 wide 2 x 10s nailed together. The beam is supported by pocket beams on each end and post/pier every 8'. Total floor is 32' x 24'. My plan is to use in floor radiant heat with Gypcrete weighing 14 lbs per sq. ft. on this floor. Will this floor be strong enough to support the gypcrete?

Second question is for the second story. I am using "Room in attic" trusses (10/12 pitch) that span 24' and will be 24" o.c. These are the typical trusses that you can get at Home Depot etc. The trusses will have a 12' wide room the whole 32' width of the house that I plan on using primarily for sleeping quarters. I also want to use the Gypcrete on this level. I believe that the trusses like this will usually support this type of weight. Will this be sufficent?

Thanks for all your help as I am doing this cabin primarily by myself when possible.

[mjpliv]

You floor joists at 12' span are fine but your beam fails. Use a four ply beam to support floor or use 4 posts instead of 3.

As far as the roof trusses go, these are a pre-engineered product and were probably designed for standard loads. I would suggest you reconsider using these stock trusses with a gypcrete floor system. Have trusses engineered with the proper loads.

[mjpliv]

Also, double check that these trusses were designed to support floor loads at 24" OC. If they are, make sure you use a floor sheathing designed to span 24" OC.

[cabinboy]

Thanks for the info and input MJP. I just called the lumber yard and they were able to get in touch with the truss manufacturer and change the specs for the extra weight. Cost was only $4 per truss. Money well invested I would say.