Ceiling, frame joints and rockwool....

knightfly · Post by **knightfly** » Fri Jan 27, 2006 9:19 am

I'm back; first, if you read through the first 2 or 3 threads listed in the REFERENCE section, it will explain a lot about walls and how they work -

Second, the only time screws cause problems with leakage is in a single frame wall with multiple layers of plasterboard. The minute you go to separate frames the problem goes away almost entirely, because the insulation inside the wall attenuates the small amount of flanking caused by fasteners; the frame and the plasterboard ON the frame act as one unit, separated from the second mass by air/insulation.

Third, acoustic caulk only SEEMS expensive; a decent household type caulk that might hold up (butyl based) here in the US costs around $4.50 per 10 oz tube; acoustic caulk comes in 29 oz tubes, and can be had for about the same as the butyl so the cost is actually LESS per foot of caulk bead.

This is generally what you should be considering for best isolation - we still need to see/hear what your roof is like though. If there's room, a separate ceiling joist system is best rather than use RC or similar - separate frames always give better isolation, and if your roof is relatively light the extra frame would allow more layers of plasterboard to be hung safely... STeve

badass_mcfunk · Post by **badass_mcfunk** » Sat Jan 28, 2006 8:07 am

Many thanks Steve, looks like a good plan

I have posted some photo's showing various aspects of the garage. I have spent a few hours looking at the reference section and also Pauls Studio diary and things certainly look clearer (I had read this section origionally, but it didn't make sense at first... I'm a drummer after all...).

You will see from the photo of the left wall by ceiling that it is a double skin wall on that side, but the inner wall does not go all the way to the top. I was planning to mortar over the exposed bit of outer wall. I'm still debating rendering the whole lot - I thought it may be acceptable just to mix up some quick setting mortar and plug all of the bits that look dodgy. On closer inspection this evening, most of the wall is surprisingly good, and I am in the process of tanking the floor / up to 1 metre up the wall with Thorseal. I think as far as the outer leaf of my construction is concerned, the ceiling is the biggest problem. After the roof was fitted (about 2 months ago) the OSB got mouldy very quickly due to damp (hence the tanking with Thoroseal). I've sprayed and brushed the ceiling with mould killer and its fine now, but may return as ventilation in the garage when the booth is built may lead to condensation. To boulster the OSB I was thinking of putting sections of plasterboard against it and fixing by wooden notches screwed into the joists then caulking, but because of the damp / mould I'm worried about putting plasterboard directly next to the OSB. Any other suggestions? Obviously if I do a layer of plasterboard directly onto joists I'm back with the '3 leaf' problem. Any cheap / quick solutions?

I've found a good supplier of acoustic caulk at only £2 per tube, so I'll be using that. The only other thing I'm unsure about is the doors. I'm thinking of 2 x solid internal fire doors from Wickes (£30 each). One will go in the main frame, the other in the stud wall (as per Steve's diagram). Can I do any kind of a small 'passageway' to keep the enterence to the booth neat? How do I do this without the wall / frame touching?

Thanks once again for all of the great advice

James

len-morgan · Post by **len-morgan** » Sat Jan 28, 2006 3:08 pm

What is above the OSB? If you had it get wet before, unless you solve that problem, I'm afraid that you might get (deadly) black mold back and you wouldn't see it after you're finished until it's too late.

Solve that problem first. As to rendering all the brick/block walls, I'd do it. It buys you isolation and isn't that hard to do. Of course, I'm not the one doing it.

len

badass_mcfunk · Post by **badass_mcfunk** » Sat Jan 28, 2006 7:36 pm

The OSB is coated with some rubberised paint stuff - I had it done properly by a roofer. It was a really wet few days when he did it so the OSB got a bit damp, and with the added problem of the garage walls being damp this caused condensation on the ceiling side of the OSB resulting in mould. I'll give it another spray, but I'm concerned about adding another layer of anything without it being totally dry, which will be hard to achieve at this time of year. Any suggestions as to what I could add another layer with, given this? The walls have now been treated with waterseal on the outside and I'm tanking the inside this weekend so it shouldn't get damp in there again.

Incidentally, I may render the outside of the left / back walls in the summer to add extra protection against penetrating damp. The right / front walls are already rendered.

Cheers

James

badass_mcfunk · Post by **badass_mcfunk** » Sat Jan 28, 2006 11:16 pm

Me again....

I've thought of a plan for my troublesome ceiling: I thought I'd paint mould resistant paint onto the existing OSB, then fix plasterboard onto it, caulk the edges and paint with anti condensation paint. What do you think??

Also - Has anyone got an effective method for holding the insulation into the frame, so it doesn't drop out the back when its being inserted? String has been suggested, but this would involve me getting a staple gun or painstakingly putting small screws into each frame section. Would a strip of duck tape running down the middle of the back of each section do the trick? I've bought 80 slabs of 1200x455x50mm Isowool to make life easier. Bit on the thin side but a friend who does loft conversions recommended it - I haven't done accurate calculations but I think I'll have loads left, so will do some double layers.

I start frame construction on Monday and have a hired hand all week, so I'll get as much done as possible. I'm expecting to have most of the booth finished by Friday.. time will tell. I'm floating a floor using delta fix acoustic battens, which seem quite cheap (£2 per metre). Cant find anywhere that stocks U boat type fixtures locally or I'd use them. Battend going onto concrete, isowool in between battens, 12.5 mm chipboard on top and then laminate flooring (if I can find some cheap). I'll leave a gap in between the edge of the battens (and everything that goes on top) and the inner booth wall so the floor is isolated from the booth walls.

Better go and finish the damp proof membraning.. Still undecided about rendering inside as I'll be doing the exterior when its warmer. I realise it will make a difference but I really dont think I'll 'need' to do it - I can always do a really thick render on the outside if I find I haven't got the degree of sound insulation that I need.

Thanks again

James

len-morgan · Post by **len-morgan** » Sat Jan 28, 2006 11:46 pm

badass_mcfunk wrote:Also - Has anyone got an effective method for holding the insulation into the frame, so it doesn't drop out the back when its being inserted?

First off, a staple gun is only a couple of dollars over here at any office supply store or Walmart. It doesn't have to be fancy.

A couple of alternatives are:

1) "Insulation supports" - These really amount to pre-cut pieces of wire that you just push between the studs and they are held in by friction. The wire is pretty stiff and I could find NO tool known to man that could cut one. They have little points that dig into the studs.

2) I ended up having to do this even with the insulation supports because they were really too long (and therefore they bowed in the middle). Get a small drill bit long enough (and sharp enough!) to drill through your studs. Drill holes about 1/8" away from the back edge of the studs every 12" to 18" vertically and then get some cheap wire and string it through the holes. It's not as hard or as time consuming as it sounds.

len

knightfly · Post by **knightfly** » Sun Jan 29, 2006 8:59 pm

I'd be really concerned about your wet OSB - when you paint over wet wood with ANYTHING, all you do is trap moisture so it can rot.

If you don't have a dehumidifier available, I'd at least direct a couple of fans toward the damp spots and a heater, and let the wood dry before attempting any coatings. Otherwise you're asking for a big headache... Steve

badass_mcfunk · Post by **badass_mcfunk** » Sun Jan 29, 2006 10:15 pm

The OSB isn't wet, and I dont think its even damp anymore - its certainly fine to touch. I'll give it a good blast with a hairdrier before painting it. I cant use a dehumidifyer in there at the moment because of the Thoroseal I've used for tanking - it may crack it. I'll give the OSB a bit of heat and paint with mould resistant paint, then cover with plasterboard and seal. Managed to find a staple gun for £6 and some garden wire to hold isowool into the frame.

Still unsure about how to do the 'passageway' from the stud wall into the framed room. I'm assuming that a gap of about 10" between the 2 walls will be ok? I'm thinking of building an enclosure using 9 x 1 attached to either wall making a very short tunnel, which will tidy up the enterance and leaving a 1" gap where the walls aren't touching.

badass_mcfunk · Post by **badass_mcfunk** » Mon Jan 30, 2006 4:41 am

...Another problem. I've screeded the floor using a self leveling compound, but having just tried laying a length of 4 x 2 down, there are some small gaps under it. I dont think I'll get the floor 'totally' flat and even without proffessional help. Will I be ok to leave it as it is and caulk around the base of the frame? Any other solutions?

Post by **sharward** » Mon Jan 30, 2006 5:09 am

Get some Sill Seal.

knightfly · Post by **knightfly** » Mon Jan 30, 2006 6:40 am

IF you can't find actual "sill seal" (trade name IIRC) you can use a couple layers of 30 pound roofing felt (heavy tar paper) - you don't need a perfect seal for the frame, the only requirement here is to have a Thermal Break. This keeps condensation from the bottom of your framing wood.

Your actual seal will be around the edges of the wallboard itself - see the two threads in the REFERENCE section for more on that.

If you can do a basic sketch of your floor plan showing where you're talking about on doorway, it'll help... Steve

badass_mcfunk · Post by **badass_mcfunk** » Mon Jan 30, 2006 9:23 am

I've attempted to show what I mean with a bad sketch... haven't had time to work this software out yet I'm afraid. Hope it makes some sense....

Cheers

James

knightfly · Post by **knightfly** » Mon Jan 30, 2006 10:55 am

James, seeing as you're just getting started with drawing I took pity and resized your sketch - if you cut out all unused white space you don't lose any detail, just makes it small enough we don't have to scroll sideways to read every post on the thread

Next time, YOU get to do it - 750 pixels wide OR LESS, please

I'm thinking you have some terms mixed up by what you're calling things in your sketch - both of your walls with doors would need frames, with plasterboard only on the inside of the inner frame and the outside of your outer frame, like the wall on the far right of this... Steve

IF you leave a couple inches between frames, that will make the total air gap around 9 inches which is about minimum for decent isolation. (Total air gap is measured from inner face of plasterboard on one frame to the next solid panel (inner face of plasterboard on the OTHER frame), so standard 2x4's being 3.5", twice = 7", plus a 2-inch space between frames... Steve