My architect created a 24"x42" hole in the 2nd floor InsulDeck for a mechanical chase access area from the 1st floor mechanical room. I will be running some HRV ducts (6 total) through that access and possibly some other utility/electrical runs through there. Just wanted to see if that is a good sized hole for that. Unlike with wood floor trusses, with concrete, you only get one shot at doing a hole and it has to be done prior to the pour. Afterwards it becomes a nightmare.

Your engineer needs to design the 'headers' to go around this opening.

If you can reduce the size to fit between the concrete beams it will be much easier, you should be able to sleeve it, pour, remove foam below and attach to the sleeves

Yeah. Don't interrupt the integral joists.

Posted By ICFHybrid on 17 May 2014 10:19 AM
Yeah. Don't interrupt the integral joists.

Unfortunately it's up to how the mechanical access lines-up with the InsulDeck I-Beam 24" o.c. portions and that is yet to be determined by the engineer.

Posted By Lbear on 17 May 2014 01:08 PM

Posted By ICFHybrid on 17 May 2014 10:19 AM
Yeah. Don't interrupt the integral joists.

Unfortunately it's up to how the mechanical access lines-up with the InsulDeck I-Beam 24" o.c. portions and that is yet to be determined by the engineer.

No it's not, absolutely not. What ICFHybrid says. Your engineer WILL work the mechanical into the space between joists, or you don't keep him on the job! Period! End of discussion!

As far as the walls go. He called for #4 bar @ 16" oc vertical and #4 bar 18" oc horizontal (Nudura forms).

Posted By dmaceld on 18 May 2014 12:56 AM

Posted By Lbear on 17 May 2014 01:08 PM

Posted By ICFHybrid on 17 May 2014 10:19 AM
Yeah. Don't interrupt the integral joists.

Unfortunately it's up to how the mechanical access lines-up with the InsulDeck I-Beam 24" o.c. portions and that is yet to be determined by the engineer.

No it's not, absolutely not. What ICFHybrid says. Your engineer WILL work the mechanical into the space between joists, or you don't keep him on the job! Period! End of discussion!

Actually, its as Chris Johnson said. The engineer can cut as many integral joists as he needs to as long as he makes up for it somehow. It's no different then making a big window opening in a wall. Just put the right sized header over it.

Posted By FBBP on 18 May 2014 08:40 PM

Actually, its as Chris Johnson said. The engineer can cut as many integral joists as he needs to as long as he makes up for it somehow. It's no different then making a big window opening in a wall. Just put the right sized header over it.

Quite true. Window openings are a simpler design issue because there the structure lines up with the load where with joists the load is perpendicular to the structure. I was thinking in terms of plumbers and HVAC guys who willy-nilly cut joists when they get in the way. When I designed and built my house I was able to line up all the mechanical to fit between the joists. Did have to do some finagling of fixture and equipment placement, but nothing significant. The only joist I had to cut out was for the crawl space access, and that was in a short joist with light loading so transferring the load from the cut joist to the others was no concern.

I'm only vaguely familiar with Insuldeck but I would think that fitting in headers and adding reinforcements to make up for the cut joists would be complicated enough to make one think twice about doing it.

Obviously, if the access hole is close to the supported end of the joist it'll be a lot easier to adjust for it than if it's near the center of the joist.

•••I would think that fitting in headers and adding reinforcements to make up for the cut joists would be complicated enough to make one think twice about doing it.•••

Quite true. Just because we can, doesn't mean we should ;-)

We put staircase openings thru Insuldeck a lot larger then your mechanical opening, it's usually adds to the cost as you are moving loading around. It can be done, but I would look for the easiest way possible without interfering with the concrete beams as this is where the costs start to rise.

Also, you need your architect to co-ordinate all this, that is there job, the SE will design the Insuldeck, the mechanical engineer will design his stuff, the architect is suppose to review and return to each consultant for revisions/updates when things like this arise and are not practical. You need value engineering on every project...especially these days