French drainage system in Basement, how to handle?

I'm looking to finish my basement for my sound proof studio. Around the edges of my new home's basement is a french drainage system. However, it currently has some filler. My home inspector suggested removing it so the drainage system could be used. He said when I finish the basement to use vapor barriers first to trap the moisture and send it to the french drain. It's a little hard to tell how thick it is because some of the poured concrete goes over whatever it is filling the drainage system. I would need to chizzle that away to remove it. It looks to be about 1/2" or an 1" wide around the edges of the basement. How should I handle this when building my sound proof studio walls? I've read on this web site to never use vapor barriers in the basement interior ever. Should I leave the french drainage system filled in for the section of the basement where the studio will be? Should I build a frame with some of that drywall that can handle water on the outside (next to the concrete), and then insulation, and then 3 layers regular drywall on the inside? I'm just not sure how to handle the wall against the concrete... any help??

First, check out the Building Sciences papers linked in the REFERENCE section, specifically the ones under "mold" - here's the link http://www.buildingscience.com/resources/mold/ The bottom 3-4 links have a lot of info/drawings, etc. Speaking of which, do you have a sketch of what is located where in your basement? I'm not clear whether your french drain is inside the basement walls or outside, etc - I also need to know how much space you can afford between your inner, new wall and the basement wall, whether you have(or plan to get) a dehumidifier, what(if any) power ventilation you intend to use, etc - write a "book" if necessary, the more detail you give the closer I can come to a workable solution. My personal favorite is to mount inner wall frames away from the concrete walls, use pallet strapping across the inside of the studs, fill just between the stud cavities with standard fluffy fiberglass UN-faced insulation, fasten the wallboard layers, and find a place/way to install a circulation fan and dehumidifier in the basement (along with double doors) so that the inner door can be left open and the fan/dehumidifier left on at ALL times except when actually using the studio. If that sound feasible to you, I can elaborate; but I really need a sketch showing your space and proposed construction, so we have a starting place... Steve

Thanks Steve! I haven't done a sketch of this kind before...so i'm gonna work on doing that, and i'll post it once I get something that looks good and will tell you as much as I can. Thanks a lot!

Steve, I never did one of these sketches before.... can you recommend any free software or something already on windows to do these drawings? To what scale? 1/4 inch = 1 foot? Thanks!

Sketchup.com or smartdraw.com

Doh...i already drew up something as best I could with word. Can you tell me if this is acceptable? clear enough? It's not the prettiest, although it looked better in word than in paint after I copied it over (for some reason). I'm gonna use the numbers to explain the drawing... 1. This is where the studio will be. It's 7 feet, 6 inches high. I’m thinking about doing the live room/control room in one so that I can get the most out of this small space. 2. This could be a place to have storage. The size doesn’t matter too much. But it gives me the chance to have 2 doors to increase isolation and get some use out of that space. I would store things here during mixing…movable acoustic treatments, mic stands, ect. 3. These dark lines are the only existing walls. They are poured concrete. On the inside, there is a 1 inch wide French drainage system currently filled in with something and not usable. It’s basically a 1 inch trench around the inside of the room that slopes towards the end with the sump pump. 4. This is where the sump pump is. The house has been flooded once because the sump pump couldn’t keep up. I’m re-grading the lawn to push water away from the house. It’s not in a flood plain. I’m also installing a second, battery powered sump pump. 5. Furnace/Air 6. This is where a duct run from the furnace to a vent on the first floor. It hangs down in the basement about 12 inches. 7. A circuit breaker is here. Since I will need access to it, I was thinking of adding walls/doors diagonally across each corner on this end. Using them for storage and access to circuit breaker on the north side. The south side will be to help keep symmetry and additional storage...maybe to isolate the computer. Another idea I think, would be to have someone relocate the circuit breaker...but I don't know how possible and how expensive that would be. 8. There is a small window here at the very top. I will have to close it up for isolation. It’s about 12 inches tall and 24 inches wide. Any more information I can give you? North of the north studio wall is where the 2 car garage is. I think this wall will provide better isolation than the others, but i don't know how to be sure. The basement is underground except for roughly the top 16 inches all the way around except where the 2 car garage is. I do have a dehumidifier that has a fan in it. I'm not sure how to handle ventilation without losing isolation though. If ventilation is only needed for giving the room a better chance of drying if wet, then I can always leave the doors open when not in use, or if too damp. If the issue is suffocating or discomfort, i'm not sure how to handle it. Is the room big enough for not using ventilation?

1. This is where the studio will be. It's 7 feet, 6 inches high. I’m thinking about doing the live room/control room in one so that I can get the most out of this small space. Probably makes the most sense in this case - 2. This could be a place to have storage. The size doesn’t matter too much. But it gives me the chance to have 2 doors to increase isolation and get some use out of that space. I would store things here during mixing…movable acoustic treatments, mic stands, ect. This could also maybe work as a vocal booth, and a plenum - see #6. 3. These dark lines are the only existing walls. They are poured concrete. On the inside, there is a 1 inch wide French drainage system currently filled in with something and not usable. It’s basically a 1 inch trench around the inside of the room that slopes towards the end with the sump pump. What kind of "something" is it filled with? if your basement needs a sump pump this drain should be functional. 4. This is where the sump pump is. The house has been flooded once because the sump pump couldn’t keep up. I’m re-grading the lawn to push water away from the house. It’s not in a flood plain. I’m also installing a second, battery powered sump pump. Good start; any other points from the Building Sciences papers that can be implemented? 5. Furnace/Air How loud is this? 6. This is where a duct run from the furnace to a vent on the first floor. It hangs down in the basement about 12 inches. This will need to be boxed in with at least 2 layers of 5/8 wallboard and insulated, unless there's a way to remove it/re-route it entirely (preferable) 7. A circuit breaker is here. Since I will need access to it, I was thinking of adding walls/doors diagonally across each corner on this end. Using them for storage and access to circuit breaker on the north side. The south side will be to help keep symmetry and additional storage...maybe to isolate the computer. Another idea I think, would be to have someone relocate the circuit breaker...but I don't know how possible and how expensive that would be. Just a single circuit breaker in a small box, or an entire distribution panel? What does it control, and how often would you need access? 8. There is a small window here at the very top. I will have to close it up for isolation. It’s about 12 inches tall and 24 inches wide. Check the window plug thread linked from the REFERENCE section. I do have a dehumidifier that has a fan in it. I'm not sure how to handle ventilation without losing isolation though. If ventilation is only needed for giving the room a better chance of drying if wet, then I can always leave the doors open when not in use, or if too damp. If the issue is suffocating or discomfort, i'm not sure how to handle it. Is the room big enough for not using ventilation? Are there ANY heating vents in the basement already? Your room is already fairly small, but if you intend to build inner walls I'd strongly consider using the space in (2) to also control air flow; I've started a re-draw of your space to show what I mean, but will have to finish later. Basically you would put the wall closest to the studio far enough to the right to allow air flow all around your inner studio walls and through the "booth", with baffled ducts built into the walls of the booth and a couple of quiet fans to help keep things moving; I would fix that french drain, use only pressure treated framing, insulation without any vapor barrier, and fasten fiberglass strapping across the inner edges of your wall studs to keep the insulation both IN contact with wallboard and NOT in contact with the concrete - this will be your air circulation zone, which will promote drying within the wall. This "zone" would be connected to ducts built into the booth (2) and from there into the rest of the basement. I'd run the dehumidifier 12/7, set its humidistat to under 40%, and only shut it off when making critical recordings in the room (same with the fans) - you may be able to dedicate a single power strip to controlling all fans and the dehumidifier for easier use. Gotta run, I'll try to finish the drawing tonite if possible... Steve

3. These dark lines are the only existing walls. They are poured concrete. On the inside, there is a 1 inch wide French drainage system currently filled in with something and not usable. It’s basically a 1 inch trench around the inside of the room that slopes towards the end with the sump pump. What kind of "something" is it filled with? if your basement needs a sump pump this drain should be functional. It's just some type of rigid fiberglass... I can easily remove it. 4. This is where the sump pump is. The house has been flooded once because the sump pump couldn’t keep up. I’m re-grading the lawn to push water away from the house. It’s not in a flood plain. I’m also installing a second, battery powered sump pump. Good start; any other points from the Building Sciences papers that can be implemented? I've read through.... that's where I saw NOT to use vapor barriers! I'll read through it again... 5. Furnace/Air How loud is this? It doesn't sound very loud....but I need to buy something to measure it. 6. This is where a duct run from the furnace to a vent on the first floor. It hangs down in the basement about 12 inches. This will need to be boxed in with at least 2 layers of 5/8 wallboard and insulated, unless there's a way to remove it/re-route it entirely (preferable) Hmmm.. I'm not sure if I would be able to re-route it. I'd have to get someone in HVAC to check it out. That would be nice...i hate that it's in there... it will be an eye sore too.. and could throw off imaging possibly because it ruins symmetry and would be reflective. I may have to build the box around it though. 7. A circuit breaker is here. Since I will need access to it, I was thinking of adding walls/doors diagonally across each corner on this end. Using them for storage and access to circuit breaker on the north side. The south side will be to help keep symmetry and additional storage...maybe to isolate the computer. Another idea I think, would be to have someone relocate the circuit breaker...but I don't know how possible and how expensive that would be. Just a single circuit breaker in a small box, or an entire distribution panel? What does it control, and how often would you need access? It's a distribution panel. I don't think I would need to access it that often. I will probably run a few outlets from it. It controls the household appliances...washer dryer. I'd like to run a few outlets from it. Are there ANY heating vents in the basement already? No, there aren't any heating vents in the basement. I think I am understanding what you are saying... fiberglass strapping? Is that like a tape that holds the insulation back from the concrete wall? [b]Another thing I was wondering about. How will I fasten the frame? I've read that you shouldn't put screws into the concrete floors or wall... is this true? I'm not sure how else to do it. [b] I'm also a little unsure about how to get my frames standing...I guess I'll have to do the ceilings last? so there is room to stand it up on end. Maybe because of my limited height, I should be building the frame in place....but do I connect it to the ceiling? Should any RC be used here for isolating the wall? [b]Thanks for your help Steve, I hope these questions aren't too basic. I've never finished a room or built a room before..and this is my first house. I've bought some books, but there are a few questions like the above, where I'm a bit confused..

Could someone please explain what a "French Drain" is? Something that gives up at first sight of oncoming water? :-) len

sort of :-) actually its a drain system around the periphery of the basement - it is a buried perforated pipe to drain water away from the foundation. http://www.extension.umn.edu/distributi ... 51-04.html

Thanks gullfo - I know what that is but I'd never heard it called that. I've also always seen them done with gravel around the pipe, never fiberglass. len

The fiberglass serves no purpose.... it's basically because the builders (6 years ago) never finished their job by removing it. The people that moved in afterwards never bothered with it. I just bought the house and will remove it so that the drain is functional.

Steve, I really appreciate what your doing for me... I'm excited about seeing the picture you're working on. So no rush, i'm very grateful, so whenever you get it posted, it works for me :) I have been thinking about how to handle the walls.... and i probably should work based off my weak link... my ceiling. If I can only make my ceiling 56 STC, then why make the walls more? (which should be relatively easy since it already has the concrete, so walls in addition to that would make the STC greater.) Since the basement is mostly underground with concrete walls, the weak spot is the window and the ceiling...more so the ceiling. The ceiling is made of engineered joists that look like the picture below (not to scale). Then after that, I drew what I was thinking for the ceiling. There is nothing in between the engineered joists, so adding that extra mass to the top shouldn't be a problem as long as the floor can handle it. The lip at the top of the joist could be used to fasten the drywall (using acoustic sealant...maybe green glue) around the edges. Or I was thinking I could screw some L brackets into the side that hold the drywall up without fastening it to the wood (also using acoustic sealant to make sure it's air tight). Any thoughts on that?

The bottom illustration is a 3-leaf design; any "beef-up" needs to go against the subfloor with NO AIR GAP. IF you can post dimensions (thickness/material of upper floor, height of engineered joists) I can give you an idea of performance. May take a day or two for the drawing, sorry... Steve

Tom, Do you have the option of using an interleaved cieling joist system? You might end up with the maximum ceiling height AND no connection to the floor joists. My studio is done this way as is Paul Woodlock's. You can end up with real room within a room and not have to worry about whether your current floor joist can carry the weight of drywall on the bottom because they won't be carrying ANY more weight than they do now. len

...although he'd still need to beef up that upper leaf, so there would be some weight added to the structure.

len-morgan wrote:

Tom, Do you have the option of using an interleaved cieling joist system? You might end up with the maximum ceiling height AND no connection to the floor joists. My studio is done this way as is Paul Woodlock's. You can end up with real room within a room and not have to worry about whether your current floor joist can carry the weight of drywall on the bottom because they won't be carrying ANY more weight than they do now. len

Len, That sounds interesting... by any chance, do you have any links to a good description on how I would do that? Did you have a thread going as you did it yourself?? Thanks!

Here's a thread showing beef-up of ceiling and interleaved (or often referred to as "staggered") joists: http://www.johnlsayers.com/phpBB2/viewtopic.php?p=20222 When I did a search for "stagger joists beef" using the "all terms" option, this is the only thread that came up. :) Although it has been covered in other threads (meaning, there's more to see/learn if you do more searching), the above thread is the one that I recall having the greatest detail in terms of illustration and pictures. 8) --Keith :mrgreen:

Thanks Keith! After reading all that...i'm not sure i'd be able to get strong enough joists to support the weight of 2 5/8" on the floated ceiling with the interleaved joists.. Looking at this calculator... http://www.awc.org/calculators/span/cal ... cstyle.asp ...though i'm not real sure about what live load (psf) and dead load (psf) actually means.... and how to figure out the grade.. but it seems that it would be difficult to get joists that would be strong enough. The room joists currently go from west to east (when looking at my picture)... so they run the long way. I would have to put joists in-between those...also running the long way.. about 19'.

I'm not the expert by any means on the whole "live load" vs. "dead load" thing... But you'll want to check out "Understanding Loads and Using Span Tables" on the American Wood Council site. :-) 19' is indeed a pretty long span... :roll: ...You might be able to shorten that span with a beam or a wall that would allow the joists to have a resting point midway through the span. If that's the case, then you'll be able to support more weight on them, without having to increase the overall height of the joists, which would obviously be detrimental to your headroom situation. Some food for thought anyway... :-) --Keith :mrgreen:

Hey Steve (Knightfly), Just wondering if you have that floor plan you drew up? If you could post it.... (if you forgot about it)! Thanks!

Actually I did forget; ever go looking for the eye of the hurricane, only to find a tornado? :cry: The drawing I started isn't complete, I may have to start over to show my intent. Your irritating duct (#6) is gonna cause problems, so it would help to know if you've decided wether you can get rid of/re-route it or not. I'll post what I've drawn so far, but it's nowhere near ready for prime time - just a concept so far, hope it doesn't just confuse things more... Steve

Yeah, I'm gonna have to leave the ducts there... :x and of course, i have the electric panel also in my way.. :x I also got another opinion on the "french drain" that my home inspector said is filled in with some foam that should be removed so it can work properly.... The second opinion said it's NOT a french drain, it's insulation between the concrete slab and concrete walls. SO.... I don't think I will be taking the insulation out. The ducts are so close to the side wall, I think I will just box the whole thing to the side wall. My room won't have symmetry though... :x It's not the best situation for a studio.... but I really need something that I can mix well in. I'm so tired of having crappy mix rooms where I can't get my mixes translating. Beneath the ducts, from the concrete to the bottom of the duct is about 6 feet, 11 inches. It runs perpendicular to the engineered joists... :x so the ducts can't be pushed up in them. (by the way, for some reason, i remembered the joists running the other way...when I wrote that one post). SO what can I do??? How big of a problem are the ducts/electrical box?

How about something like this Steve?? Isolation is only a major concern in the "live" room/"control" room. The red marks are where I could drill out holes in the stud there and place some quiet fans. One side reverse the fans to help with air flow. The main room will only have 2 leaves. Outer concrete. Inner 2X4 studs, insulation inbetween, 2 layers drywall on inside. EXCEPT where the vocal booth/closet is.... i'm not sure how to make that a 2 leaf only design without having insulation exposed on the inside of the closet. Will this hurt me????? Where the number 2 is, I could leave that as concrete?? Then the walls around the closet would be staggered 2 leaf...

Also Steve, do you think I should bother with angling the walls in my situation?