Sound proofing hollow steel fire door

Twist Turner · Post by **Twist Turner** » Thu Dec 16, 2004 12:47 am

I"ve done a search here and found nothing, I'm stuck with 3 hollow steel fire doors that need to be sound proofed in someway. I know there will be no problem sealing around the doors there seem to be plenty of products on the market for that, but I'm worried about the doors themselves.

I thought about filling them with sand by removing the hardware and filling around it with expanding foam to keep it from the locks, but the door would end up being about 300lbs when done. Lead would be even heavier.

Any suggestions of what to fill it with? Possibly pellets of blow in insulation? Mica or vermiculite? Joint compound(probably way to heavy as well). One thought I had was to fill it with structolite which is very light and used as a scratch coat for plastering walls. It dries like concrete and is fairly light, might add 40-50lbs to the doors at most, but I"m not sure about mass. I"m not sure which way to go on this, any ideas??? This is my only weak link right now.

HELP!!!!!!!!!!!!!!!!!

gdgross · Post by **gdgross** » Thu Dec 16, 2004 2:23 am

Tell us a little about how the doors are used. Is it a single door separating you from the outside world, or a dual-door arrangement? That may effect some folks answers about what you should do with the doors.

z60611 · Post by **z60611** » Thu Dec 16, 2004 5:19 am

I'm going to assume you actually want to use these doors, and don't want anything else.

This door
http://www.firesonic.com/stc_51.shtml
is a steel door that's filled with concrete, and weighs 200 lbs.

There's 3 pictures of it in use here http://www.tedwhite.homestead.com/gallery4.html
and its door frame can be found here http://www.tedwhite.homestead.com/gallery2.html

hmm. I thought it was filled with concrete, but the links say "It is constructed of a steel skin with 3 layers of limp mass lead sheets inside" and "Door has 3 lead sheets inside and is way heavy."

Actually lead sheet probably makes more sense, since doors flex, and concrete doesn't handle flexing well.

Any suggestions of what to fill it with?

Although I've seen speaker stands filled with pellets, in a steel door I'd be worried about rattles. Sand wouldn't rattle, but the mass drop around your handle hardware may be an issue letting more noise through near the handle -- perhaps you could do a Paul Woodlock and stick some 8"x8"x1" MDF on either side where the handle goes to beaf it up a bit there.

If the doors are on either side of an airlock, then you probably want to fill them with something massive.

If the doors are stand alone, then you could fill them with insulation (not expanding foam, but perhaps blow in celulose, or if you can weld then rigid rockwool) and then stick layers of something heavy on either side (not lead - health). Perhaps a couple layers of this stuff http://www.auralex.com/sound_isolation_ ... blokPL.asp or peel and stick sheets - search for item 9709T19

rod gervais · Post by **rod gervais** » Thu Dec 16, 2004 12:19 pm

Twist,

I actually have done this (and on a world class recording studio to boot) - with very good results.

You can use 8 psf sheet lead and 3/4" plywood (or MDF if you so choose).

Glue the sheet lead to the door using PL-400 (or any other decent construction adhesive)

Once the adhesive sets - attach the plywood to the assembly using liberal amounts of the 400 and sheet metal screws.

Pre-drill the plywood and door - and pre=tap the steel door to assure the screws attach properly.

If you hold the plywood 3/4" inside of the door sides and edges it will allow you to do a nice multiple seal assembly.

Add a good quality sill and drop seal and you should be fine.

Rod

Twist Turner · Post by **Twist Turner** » Thu Dec 16, 2004 2:36 pm

None of the 3 doors are directly to the outside world. One is in the lounge area behind the control room, and leads to the garage, this one is not real critical. One leads from the commercial space the studio is located in to the upstairs apt I'll be living in. This one scares me somewhat as it's in the live room, but there is a solid core door, a 10ft hall and another insulated steel door between that and the outside world. the building is 3 layers of brick, with plaster and lathe walls attached to furring strips but its a shared brick wall between the 2 buildings. The one I"m most worried about leads to a entrance way into the studio. This is a room approx 7x8 with double glass doors to the outside world with the steel door leading into the live room.

I'm just wondering if Rods advice will pass the building code here, Maybe I should just sheath them with the lead alone. Not sure how well that will hold up, it's pretty soft. As of now I have no thresholds on these because the flooring hasn't been installed, but i"m getting real minimal noise out of the front door. I"m located on a busy main street so this is actually very good. I have not ordered my magnetic weather striping yet either.

I'm up for any more suggestions if anyone has any.

rod gervais · Post by **rod gervais** » Fri Dec 17, 2004 2:53 am

Twist Turner wrote: I'm just wondering if Rods advice will pass the building code here,

I don't know where "here" is - but - unless they are required to be a rated tested fire door assembly - modifying them is not a code violation.

Maybe I should just sheath them with the lead alone.

Now THAT would be a code violation - lead is a very large health hazzard - and exposed lead would violate health codes.

Rod