Quick Questions - Door, Window

Hi everyone, I am building a window - I've done it in three steps so far, basically a glass sandwich: 1) build frame <img src="http://www.omnitonestudios.com/johnsayers/pic1.jpg"> 2) put glass on frame, mount equally thick wood to frame <img src="http://www.omnitonestudios.com/johnsayers/pic2.jpg"> 3) put top frame on bottom frame <img src="http://www.omnitonestudios.com/johnsayers/pic3.jpg"> I did the wood attaching by using Gorilla Glue and wood screws. I set the window in C.R. Laurence Silicone Sealent 33S, which the glass manufacturer suggested. The gorilla glue is some great glue that expands 3-4 times in size and foams up as it sets; takes 3 to 4 hours to set. I bought 6 tubes of USG acoustical sealant - should I use this to caulk the window? I was thinking of doing it where the window meets the top and bottom "frames." I would probably need to add trim or something to make it look nicer if I do caulk it. Any advice on that? _____ The other question is, how do you mount MDF to a pre hung hollow core door? Do you just use glue? What type of glue should be used? Should nails be used to supplement it? Thank you for your help! I am actually taking a ton of pictures and assembling/writing a "how-to" guide for building a vocal booth. I have been reading over tons of posts on this subject, and haven't needed to ask many questions so far, based on using the search feature. I'm going to post the how-to, and then maybe some of you could critique it and add suggestions. - John

So, you're ending up with a single pane of glass sandwiched between two wood frames, with a wood filler around the perimeter of the glass, is that right? Is that ALL you will have in your window? How thick is the actual glass? Laminating MDF to a hollow core door - first off, these typically only have maybe 1/8" thick skins on either side of a cardboard honeycomb inside, with solid wood around the perimeter to fasten hinges, locksets, etc, to; so nailing or screwing the MDF wouldn't work too well from a physical standpoint; from an acoustic standpoint, you don't want metal fasteners running through the multiple layers of a sound barrier if you can help it, they flank noise through otherwise decent material. Probably one of the better ways of laminating MDF onto a door is to use Resorcinol glue; it's a 2-part glue made up of a liquid and a powder, and the stuff is amazing. http://www.dap.com/techbulletins/00030205.pdf The downside is that it takes quite a lot of pressure and at least 70 degrees; I would get some large C clamps and clamp the edges of the door HARD using long 2x4's on edge for stiffness, and put C clamps every foot along the edges; doing a door would require about 16 large C clamps, which very few dedicated wood workers even own. An alternative is, if you have some heavy saw horses and/or a big stack of gypsum wallboard around, you could stack about 20 sheets of wallboard on top of the door til it's dry. Or, you could use contact cement... Steve

Hey Steve, Thanks for the reply - Yeah, the window is just as you described - one piece of glass is 1/2", the other is 3/8" We actually bought a 30" solid core door, and are possibly going to attach some MDF board to it. Do you think we should? I was going by things you mentioned in another door thread, where you presented the idea for modifying a hollow core door. We've got commercial hinges for the framing of the door to hold it up. So, I'm not sure if we should put the MDF board on the door or not. We're trying to finish tomorrow, so we'll see. If anyone can chime in with an answer that would be very helpful. I can't afford the zero international drop seal right now, although I will try and get that later on. The next thing I have to figure out is some quick and easy ventilation, perhaps through two long tubes with several quiet computer fans pulling air in and out of each. We'll see. As usualy any advice is appreciated - thanks! I will also have tons of pictures of this, for future help of forum users. - John Shryock

Solid doors, even with perfect seals, only end up at maybe STC 32 for a 1-3/4" exterior, SLAB type, solid core door; since it is solid, for a single door you're looking at mass law for the TL values; so increasing the door from 1-3/4" to 2-3/4" will only increase the performance by about 2-3 dB - generally not worth the effort of adding the MDF. If you have the space, you'd get a LOT better performance by adding an air lock and a second door... Steve

Thanks Steve, Save us some work - we won't be adding the MDF board, but it's a shame it'll be such a low STC. Oh well. This thing has taken forever (vocal booth) and it'll be good to finish today... if we do! STC 30 is better than STC 0. Won't be very good for multitracking, though... dang. Anyways, thanks again. - John