The leaves, the doors, the insulation

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SoWhat
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The leaves, the doors, the insulation

#1

Postby SoWhat » Thu, 2020-Jun-25, 13:02

Greetings all,

I have tried using all sorts of search terms on different forums for the answer to this, but have been thus far unsuccessful. Worst thing is, I'm sure I've read it somewhere.

There is the outer leaf with its door, the air gap with its insulation, and the inner leaf with its door. What covers the the visible insulation filling the air gap without connecting the two leaves together? Fabric? Magic? "If-you-ignore-it,-it-will-just-go-away"?

Thanks.

All the best,

Paul



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Starlight
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The leaves, the doors, the insulation

#2

Postby Starlight » Thu, 2020-Jun-25, 16:56

Here is my doorway with the brick outer wall, insulation and a steel stud plus OSB and (yet to be added) plasterboard for the inner wall.
0802.jpg

Here is the textile I bought to close up the gap you mentioned, Paul. I went to my local textile shop and asked if they had any textiles that were waterproof. I will wait until the carpenter arrives to fit the inner door frame (so that he can see again where the stud is to connect the frame to) before sticking this textile in place.
LP0720.jpg

I may be going for overkill as I am sure that just shoving some plastic sheet around the insulation and tucking it in would probably achieve the same result. It kind of depends on where the gap between your frames will be relative to the insulation and how big it will be.



SoWhat
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The leaves, the doors, the insulation

#3

Postby SoWhat » Thu, 2020-Jun-25, 17:28

Greetings Starlight,

Thanks for posting the photos. I assumed that fabric was the way to go, and I didn't even think about the waterproofness (yes, that's a word, or it is now) issue. Methinks I will try the plastic sheeting with fabric over top. I might have my wife paint something cool on the fabric.

I must say the yellow is a real head-turner! Are you going to continue the vibrant, bold colors in the studio?

All the best,

Paul



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Starlight
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The leaves, the doors, the insulation

#4

Postby Starlight » Thu, 2020-Jun-25, 18:56

SoWhat wrote:Source of the postAre you going to continue the vibrant, bold colors in the studio?

The textile shop offered me black, dark brown or yellow. Only a couple of centimetres (or about an inch as you're in PA) will show between the two doorframes so I thought yellow would be more fun.

The studio is probably going to be a neutral pale colour as the room has no windows. Philips Hue striplights will be where the colour comes from, at least that's the plan at the moment.



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ericwisgikl
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The leaves, the doors, the insulation

#5

Postby ericwisgikl » Thu, 2020-Jun-25, 19:19

Hi Paul,

I was having the same doubt and I think something that could be done is putting osb, drywall and/or whatever you are using for the inner leaf, attached to it and making the gap smaller, letting about half an inch gap, in a way that it can be sealed then with baker rod and caulk.

What do you think folks? Would it work fine?

The method Starlight shows above is fine too, but I think it can't be done in every situation. Only with wood doors and windows, where you can attach the fabric before putting them in place. But with aluminium or pvc doors and windows, I think it's a little bit harder. Maybe I'm wrong anyway.

- Eric -



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The leaves, the doors, the insulation

#6

Postby SoWhat » Thu, 2020-Jun-25, 20:08

Greetings Starlight,

Agreed on the "fun" factor. Yes, neutrals seem to be the best choice. We used a warm white in our basement family room remodel that I will like use in the studio.

Actually, I'm pretty good with metric measurements. It's probably from cooking a lot (I weigh everything in grams), and from spending so much time in the UK where Imperial and metric are interchanged as much as French and English in Montreal.

All the best,

Paul



SoWhat
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The leaves, the doors, the insulation

#7

Postby SoWhat » Thu, 2020-Jun-25, 20:17

Greetings Eric,

I'm trying to picture what you mean. Can you do a quick drawing?

Thanks.

All the best,

Paul



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Starlight
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The leaves, the doors, the insulation

#8

Postby Starlight » Fri, 2020-Jun-26, 02:22

ericwisgikl wrote:Source of the post... and making the gap smaller, letting about half an inch gap, in a way that it can be sealed then with baker rod and caulk.

What do you think folks? Would it work fine?

In theory a gap is a gap but in practise you only need a small amount of movement or error and that half inch could become less and mean the inner and outer walls touch. Over on Gearslutz I read recently where someone intended to leave half an inch between studs and avare criticised that person, telling them it was too small, and to leave the industry standard one inch gap. I would think the same applies here. For me, one inch of caulk for the 5 metres (16 feet) around the door frame would be really expensive and require lots of fiddly work to layer it, whereas the textile cost me 11 euros ($12, £10) and I will be able to glue it in place in a matter of minutes. In your situation I would be looking for something easier and cheaper than caulk and backer rod.



SoWhat
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The leaves, the doors, the insulation

#9

Postby SoWhat » Fri, 2020-Jun-26, 08:45

I read Andre's post as well. I get nervous about small margins-for-error in anything, let alone where a potentially expensive mistake is concerned.



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ericwisgikl
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The leaves, the doors, the insulation

#10

Postby ericwisgikl » Fri, 2020-Jun-26, 12:52

Starlight wrote:Source of the post For me, one inch of caulk for the 5 metres (16 feet) around the door frame would be really expensive and require lots of fiddly work to layer it, whereas the textile cost me 11 euros ($12, £10) and I will be able to glue it in place in a matter of minutes. In your situation I would be looking for something easier and cheaper than caulk and backer rod.


It's true. Maybe half an inch is a little bit small and indeed a small margin-for-error. You're right Starlight, it's a good point to take into account the cost too.

Greetings!

- Eric -



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The leaves, the doors, the insulation

#11

Postby endorka » Sat, 2020-Jun-27, 08:33

I've read about several approaches to this. At one extreme Rod Gervais advocates a continuous through jamb, i.e. no gap at all. His experience indicates that the loss of total isolation is not that much, and the benefit of the resulting sturdier door frame useful for hanging very heavy doors. However, I note he seems to prefer a single heavy door approach in general.

Stuart seems to prefer the double door approach where possible, and from examples he has posted employs decoupling between the inner and outer leaves. I imagine this would provide greater isolation than the single door and through jamb approach.

(please correct me if I am wrong on any of these by the way - just citing from memory)

Whatever you do, something that might be worth considering is preserving the fire rating of the wall assembly. Gaps in partition walls for ducts and so on tend to work against this, and generally must be fitted with something of equivalent fire rating. Intumescent pipe collars and so on. What is required all depends on local building regulations pertaining to the particular use of the property.

I have no idea where the gap at the end of a partition wall fits into this. In theory, with both (fire rated) doors shut and properly sealed the fire rating is preserved. But as soon as one is open, it might not be. Of course the same laws that mandate fire rated walls in commercial and domestic properties (where applicable) will also likely mandate self closing doors...

In practice insulation between the wall leaves is likely to be fire retardant, and maybe a single leaf provides enough fire resistance. I would definitely still check the regulations about this though.

Would flame retardant rubber across the gap do the trick here?

All this is just conjecture and ponderings by the way, reality may be very different!

Edit: I think the rules in the UK are very fussy about the exact construction of fire rated door frames, so definitely worth checking these things.

Cheers,
Jennifer



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Soundman2020
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The leaves, the doors, the insulation

#12

Postby Soundman2020 » Tue, 2020-Jun-30, 14:50

That's a great point about fire-rating, Jennifer. Very important.

Building codes and fire codes do seem to vary a lot, but using fire-resistant (or even better: fire retardant) materials in your studio is just common sense. Especially with fabrics: if the fabric you like is not fire-resistant (a.k.a. "flame resistant"), then there are chemical treatments you can apply to make it so.

From this point of view, mineral wool insulation (often made from slag) is preferable to glass wool insulation ("fiberglass"), which is made from sand. You'd think that, since both of them are basically just rock, and therefore inert, that it wouldn't matter, but it does. In general, mineral wool insulation is more fire resistant that glass wool, and it is also deals with water much better. Fiberglass insulation that gets wet usually ends up as a useless soggy mess, but mineral wool handles it better.

Anyway, getting back to fire code: you often see that fire code does allow inserting a strip of mineral wool between framing sections to comply with fire ratings. It does help prevent flame spreading across gaps. In most places, it should probably be acceptable to just have mineral in the gap between door frames, covered with flame-resistant fabric to make it look pretty.... But don't take my word for it! Check your local building codes, and if there is still any doubt at all, then call your local building inspector and ask him: After all, he's the guy who will have to sign off on your inspections! Do what he says, not what I say.

Now, for the gaps around windows, that's a little different, since the windows are sealed in place and will never be opened: from that point of view, they are just extensions of the wall surface. But that exposed gap is actually rather important, acoustically, for isolation! A substantial port of the isolation of a studio wall is due to the insulation between the leaves.... but for obvious reasons, you can't have insulation between the two panes of glass! The best you can do is have a large surface area of insulation exposed around the edges of the window. It does help. You can also compensate for the lack of insulation by increasing the mass (surface density) of the glass, so it is a bit higher than that of the wall itself, and also by setting the two panes as far apart as possible, thus having a larger air gap between the glass panels, than between the sheathing panels.

One more thing with windows: condensation. The air trapped in the wall cavity will have some moisture in it (humidity), and that can condense on the inner surfaces of the glass... where it is impossible to get at it! It will fog up the glass, so you can't see through it, and it will also leave marks on the glass when it eventually dries out. Not good. The solution is: desiccant. You need to place some desiccant in that gap between the glass panes, to adsorb the moisture out of the air. Silica gel is good for this: that's the same stuff you sometimes see in small white envelopes inside the packaging for new electronic equipment, cameras, medications, shoes, and suchlike. Silica gel is not the only desiccant that you can use, but it is inexpensive, easy to get, and very effective. There are equations that tell you how much of that you need inside your window cavity, based on the volume of air you have trapped between them, but a simple rule of thumb is: You need at least 200 grams of silica gel beads per cubic meter of air space in the cavity. That is not a lot, because the surface area of the granules is quite high. You do need it! If you look around the edges of sealed double-glazes window units in your house, you will probably see a perforated metal strip around the edge: inside that, there is probably some desiccant too! Even though they take great care in the factory to keep moisture out of that cavity, they still do put in desiccant, just in case. So you should too! But using perforated metal strips is a pain... so...

A simple method is to make a sort of "tray" from thin metal or plastic, that partly covers the gap between the two window frames (but only touches ONE of the frames!), and scatter your desiccant all long that, then put your breathable fabric over that, so it is hidden from sight but also exposed to the air between the panes. Usually it is enough to just do that along the bottom of the window, but for large windows or damp climates it's a good idea to do a second tray across the top, and drill small holes all over it, so air can circulate better. In this photo, you can see that an area has been routed out of the window frames to receive the desiccant tray:
window-framing-with-desiccant-tray.jpg


Another note about silica gel: If it is the type that changes color, make sure it is the right color before you put it it! Either blue or orange, depending on the type. But never pink or green! If it is the wrong color, or if it is not colored at all and you don't know if it is dry or saturated, then heat it in an oven set to about 125 °C (about 250°F) for several hours, then put it in the cavity and seal the glass in place as soon as possible afterwards. Silica Gel is pretty inert: it's actually similar to quartz or sand, chemically, so you can put it on or in pretty much anything. Those labels that say "Do not eat! You will die!" or whatever, that you see on the packs of silica gel in cameras, shoes, pills, handbags, etc. are because of the additives that they put in so that it changes color when dry / damp: That color-change chemical stuff is poisonous, but not the actual silica gel itself. It's no more dangerous than sand. If you get the stuff that does not change color, then you could use pretty much anything you want to make the "tray" to hold it. If you get the color-change stuff, then maybe plastic would be the best choice: you can find plastic and metal "profiles" of various shapes and sizes in hardware stores, such as Home Depot, and use that to make your trays, then glue and staple it to one side of the frame gap. Don't use wood for the tray, as that can warp with humidity, and there might also be unwanted reactions with the color-change chemicals. Spread out the silica gel as much as you can in the "trays", to get maximum surface area exposed to the cavity air.

And do use flame-resistant fabric over it!

- Stuart -




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