Building a 4x6 hidden room

[budderfly]

Welp, lost a couple hours. Cut my finger to the bone cutting duct work and had to run to the ER for a few stitches. It's not a project until you draw blood - that's what I always say. :)

 

[budderfly]

:eek:

 

[mmg-az]

ouch officially on! great job on project

 

[budderfly]

Here's a shot of the finger today. :) I'm taking a break and doing some work for my day job and I'll be back on the build tomorrow - with a new spiral cut out tool. ;)

 

[ttystikk]

You know, some people just take pictures to remember their projects by...

j/k- glad it wasn't worse. The stitches look as neat and professional as the rest of the buildout-

 

[budderfly]

Ok, so I spent a couple days doing the day job and now I'm back to the room build.

Here's some shots of me setting up the ventilation taps.

I started cutting holes in the duct with a snips. It worked, but tore the metal more than cut it and left nasty edges. Not precise enough for the take-offs.

Also, I'm cutting a couple holes so that I can feed in and glue up duct lining, sound absorbing insulation.

After the fiasco with my finger I used a rotary cut-out saw and the snips to cut out the two top takeoffs.

Here's the exhaust duct - 8". I had some spare flex duct that was decently heavy, so I just picked up insulated wraps from Home Depot (5' lengths). I want the insulation more for sound but heat is important too - I'm aiming for handheld flir invisibility.

Here's the exhaust line set in place. Really tight squeeze to get that takeoff seated. I'm also running the intake in that same joist cavity - it's going to be stuffed but I have faith it'll all fit. :)

This is Mass Loaded Vinyl backed with, iirc, closed cell foam. All together it's about 1.25 lbs per square foot. The foam absorbs mid range noise and the heavy vinyl stops vibrations from transferring. I'm going to be wrapping it around the insulated ducts in the joist cavity. Ha, if it fits!

Getting awfully full up there.

Here's the intake line. Same deal, leftover flex & new insulated wrap. Different shaped takeoff. Gotta say looking at it at this point it doesn't look like it's going to fit...

And here's both lines hooked up, the takeoffs are taped nice, and the MLV is around most of the duct (I add some underneath to wrap all the way around later).

It was not easy to pull the last duct through, but they do fit. It's stuffed like thanksgiving turkey but she's good to go!

 

[budderfly]

Alright, got a little more to show you. Here is how I am reducing the noise that travels through the house's HVAC ducting. It's no good if the exhaust blowing into the duct echos throughout the house. Without extra treatment, you would be able to hear the air/fan noise at many points in the house when it is quiet. I believe I can change that.

Earlier you saw me cut large access holes in the ducts while installing the take-offs. I am going to use those holes to install this insulation batting.

I highly recommended this stuff. It's acoustic duct liner, similar to Owen's Corning QuietR duct liner but house brand of a local place. The resonance in the ducts was night and day after installing this.

I started by going 2 feet down the duct over the bathroom. (later, and i unfortunately didn't get a picture, but I glued a piece of insulation below this exhaust entrance across the duct to direct the air flow down the duct away from the main hvac unit.)

I went 4.5 feet across - the width of the roll - the entire width of the hidden room. Then I added a couple more pieces to bring the insulation all the way to the end/turn in the vent. All the access panels are covered in insulation.

Patches are up. These were cut partially with a jigsaw & metal blade and partly with snips. I have concluded sheet metal is just a royal pain in the ass, at least for me.

I had some left over dynamat-like material, I believe it's called a mass constrained damping layer or something. Anyway - the insulation made a very large difference in the resonance of the duct. But with the dynamat, now the ducts are just dead. Thud. They are going to dissipate the sound energy very well, and after duct mufflers and lengths of insulated flex duct I think all noise will be effectively eliminated within 4 feet of the taps.

 

[budderfly]

Progress has been a bit slow going - I'm having some trouble getting the door to work the way I want, and I had to redo a couple little parts in order to get the level of precision finish that I wanted. Might as well do it right, ya know.



Here's a shot of the door frame I built. One tip I learned, build the frame in place to make sure it fits the door frame squarely.

I used a router and a straight cut bit to shave off 1/2" of thickness for the drywall to recess into. It was quite messy, loud, and took a long time, but I don't know a better way to do it.

I ended up just holding the frame together with some metal braces. After routing, I couldn't drive any screws through like you would when framing a wall without splitting boards. In general, 2x4's don't take to well to any cutting other than cutting to length. The braces worked well, and once the drywall was in the door is was pretty solid.

Right now I'm having some trouble with the magnets. I haven't been able to get them mounted close enough to work. It's also too damn difficult to pull the door shut from the outside with no hand-holds.

The door's a major part of the build so I'm taking my time with it right now.


Here I'm drilling some holes through a piece of drywall for the fake piping to go through.

I've put the piece I am cutting on top of another scrap piece of drywall. When using a hole saw or spade bit on drywall I found the surface you cut into on top comes out pretty clean, but the back surface blows out pretty bad. This is solved by simply laying the piece on another and cutting through so that the piece under prevents the backside from tearing out.

Here's the drywall up for a test fit.

And finally the copper is all soldered in place and the PVC is glued up. Behind the new, fake wall you can see the old wall and its piping. The point is to make the new, fake wall look very similar to the old wall. I think the fake piping goes a long way towards making the wall look legitimate.

Here's the backside where the pipes go through. They don't actually extend beyond the drywall on the bottom because I'm going to Green Glue a second sheet up over everything. On top, you can see I put some elbows in - those are to keep the pipes in place and prevent anyone from pulling them out easily/accidentally.

And finally after I green glued and screwed up a second sheet. of drywall.

So, it's coming along. But the door is a pain, and I have to finish that before I can go further - the door basically gets built into place - as far as I can envision it will be impossible to remove once the inner wall gets built, as there will only be a few inches between the two walls.

 

[EVOKE]

you have been doing an awesome job on ur project... its coming along great and you really went all out detailed work... i cant wait to see ur finished project... peace and respect...

 

[SodaLicious]

I would hinge the outter wall if possible, or a section of it anyways, so it swings out enough for you to get in. Thats how mine was.

 

[budderfly]

Ok, I hit a milestone here tonight. The door is workable and in place!! There's still some improvements to be made, but I can continue on past the door until I get some more magnets, lol.


So the first thing I'll show you is the door frame with the magnets attached. I used spade bits to drill recessed holes for the magnets.

The larger magnets at top are 7/8" diameter and are rated at 10 lbs holding force. The smaller magnets are 5/8" dia. and rated at 7 lbs holding force. I also plan to get 1" dia. 20 lbs magnets for the door on the inner wall, now that I have a sense for how strong they. These are all from K & J Magnetics, and their site is good - lots of options, good info, competitive prices from what I can tell and quick shipping.

When you have these magnets in your hand, they are very strong. But once they are mounted they are not perfectly close together (unless you're a wizard at building shit), and so they do not seem nearly as strong.

The large magnets at top can snap the door shut from a few inches, and they take a good push to open - but this is by no means any measure of security! I will be using a security electomagnet with 600 lbs holding force (or maybe 1200) to hold the door closed. The permanent magnets are simply backup.

I also plan to order more 5/8's magnets and drill the holes deeper to stack 2 magnets. That will increase their holding force significantly. I think having the four together in a plane also increases the total force, but not nearly as much as stacking along the magnetic axis will.

A couple of the larger magnets cracked from screwing them in too hard. Bummer. They warn you that they are very brittle, and they can go a little nutso when the come apart...

Here's the door frame. I initially tried magnets on both sides. You can order them in pairs, N pole & S pole up. When stuck straight together the bond is much stronger, but on the door it was really impossible to line them up well enough, and sometimes you'd get repelling edges.

It worked far better to use metal plate. Again, you could make this thicker, or use different materials, to create a better bond.

On the right side of the door I found I had a gap and could see the magnets. I pulled out the chisel and countersunk a rectangle for the plate. With the plate flush the gap is gone and you cannot see the magnets, but I'm not getting the best hold, either. I believe stacking the magnets 2 deep will fix this, but I have to be careful to not make it so strong the wife can't open it, ha!

Here it is closed up with the middle stud just propped up in place. What do you think? Stealthy?

Tomorrow I'll be laying base plates for the interior walls and building those out.

I would hinge the outter wall if possible, or a section of it anyways, so it swings out enough for you to get in. Thats how mine was.

I've been thinking about that, but I have trouble envisioning how I would hide an out-swinging door in this wall. I've seen some great out-swinging bookshelves, but they have trim to hide the gap needed to clear the frame. I'm not sure how I'd hide the gap.

I think I'm going to go with what I've got for right now. It's working, and while a swing out door might be easier to use and save some space, designing one for this spot seems challenging. But if you have any ideas or resources on what kind of hinge I might want to look at I'm all ears.

 

[TexBud]

That last pic looks great! Looks like load bearing wall. Does your stealth door push in or pull out? Either way, you could add shelves to the whole entire wall including , at least one, to door. The one on the door could double as a handle/grip to help open/close door. Then you fill the shelves with what evers; only place a couple of (light/don't mind moving) items on the door shelf. Better yet, glue the items to the shelf like a coffee can(s) ect. you know stuff you'd normally see in a garage or basement. Talk about stealth then!! Just an idea. I know you have more work to do.

Keep it going , growing, and happy harvesting!

 

[budderfly]

That last pic looks great! Looks like load bearing wall. Does your stealth door push in or pull out? Either way, you could add shelves to the whole entire wall including , at least one, to door. The one on the door could double as a handle/grip to help open/close door. Then you fill the shelves with what evers; only place a couple of (light/don't mind moving) items on the door shelf. Better yet, glue the items to the shelf like a coffee can(s) ect. you know stuff you'd normally see in a garage or basement. Talk about stealth then!! Just an idea. I know you have more work to do.

Keep it going , growing, and happy harvesting!

Thanks! It's the culmination of a lot of work so far, and was a make it or break it moment. Bad door would've been a show stopper. I've been thinking through every board in this whole room obsessively for the last several months. It took a while, but I have a solid vision of nearly every detail I have yet to execute. And so far the build out is coming pretty close to the picture in my head.

The door pushes in, then you slide it to the side in between the fake wall and the soon-to-be inner wall. It's a pretty tight squeeze so there's not really room for much of a handle. It's a little awkward now, but I have an idea involving more magnets as removable handles using a steel strip behind the drywall. ;)

 

[budderfly]

Alright, made some more good progress day before yesterday, but at the expensive of sleep. I need some rest; I was getting so tired that I kept running into things accidentally and hurting myself. Don't even ask about my stubbed, purple toe.


So I framed up the inner room. Nothing too special.

Here's the soffit frame. You can just barely see it in the photo - but where I screwed 2x4's into the floor joists, what I did was cut a strip of the foam-backed MLV and put it between the 2x4's and joists in order to reduce transmitted vibrations. A little detail, but the little things add up.

Now I'll show you something cool! Roxul Safe-N-Sound insulation.

It's mineral wool insulation, and similar products are made by several companies. It's quite easy to work with, it can be cut easily with a bread knife like you see in the pic. It is a little messy, but not irritating like fiberglass.

Here's a couple shots of it installed. Many of these stud cavities are not standard width, only a couple are actually 16" oc. But the roxul is easy to cut not only to length but to width, or around obstacles.

If you stand in front of a covered part and bark a few words, then stand in front of an uncovered part and do the same, the difference is very drastic. The Roxul is most certainly absorbing a lot of sound.

 

[Smoking Gun]

Budder, the project is really coming along very nicely. I am excited to see how the final product comes out. The space only looks a bit different than how it was originally arranged. Did you have to shift where the water heater lives? And did that involve any change of piping?

 

[EVOKE]

looking awesome there budder...;)

 

[budderfly]

Budder, the project is really coming along very nicely. I am excited to see how the final product comes out. The space only looks a bit different than how it was originally arranged. Did you have to shift where the water heater lives? And did that involve any change of piping?

I did not have to shift the water heater. It's a bit snug to squeeze through, but not so tight to be a tell. That is, you wouldn't be like jeez what the heck this is so close (unless you were pushing 300 lbs, so like 60% of the local cops, lolz).

I may move it later just to give it a little room, but before moving it entirely I can gain back several inches by eliminating some of the black pipe feeding gas to it - the pipe has some unnecessary bends and stands of the heater quite a ways.

If I do move it, I will of course have to change the water pipes and exhaust chute a bit.

 

[Smoking Gun]

I did not have to shift the water heater. It's a bit snug to squeeze through, but not so tight to be a tell. That is, you wouldn't be like jeez what the heck this is so close (unless you were pushing 300 lbs, so like 60% of the local cops, lolz).

I may move it later just to give it a little room, but before moving it entirely I can gain back several inches by eliminating some of the black pipe feeding gas to it - the pipe has some unnecessary bends and stands of the heater quite a ways.

If I do move it, I will of course have to change the water pipes and exhaust chute a bit.

Gotcha, for some reason I thought it was back against the original wall.

How is that finger doing? It was a pretty gnarly gash. But stitches are for wimps, some duct tape would have fixed it up just fine. (Man the internet really needs a sarcasm button).

 

[budderfly]

Gotcha, for some reason I thought it was back against the original wall.

How is that finger doing? It was a pretty gnarly gash. But stitches are for wimps, some duct tape would have fixed it up just fine. (Man the internet really needs a sarcasm button).

Finger is good, despite being deep it was not a bad cut, never even got sore or hurt really (unless you whacked it). I took the stitches out yesterday. DIY ;) No health insurance and all, silly to pay out of pocket to remove a few stitches imho.

 

[Smoking Gun]

Can't disagree there. It was a very clean looking cut. Glad to hear it has healed up well. Now get back to work, we want to see this room in action.