Two questions regarding doors: solid and hollow core.

How thick should my walls be, should I float my floors (and if so, how), why is two leaf mass-air-mass design important, etc.

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PD
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Joined: Thu Jun 17, 2004 5:09 am
Location: San Francisco

Post by PD »

Steve, I have the new plan with its update here:
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=1862

Thanks for giving it a look.

Wow.. I'm poised to break the double-leaf rule right off the bat on all six surfaces- guess I have to make the best of being a sonic outlaw.. :mrgreen:

Perry
knightfly
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Joined: Sun Mar 16, 2003 11:11 am
Location: West Coast, USA

Post by knightfly »

Perry, while it's true that building a full room-in-room is probably your only sure way of getting enough isolation (even if you end up breaking the m-a-m rule, since you have no control over parts of your existing construction) doing so can be DEADLY if it's either done wrong or done where it should NOT be done -

Keep in mind that a floated floor places some HORRENDOUS pressures in small areas, similar to the concept of a woman in high heels causing major floor damage due to the high point loads involved - I won't begin to recommend such a project without knowing EXACTLY what your floor is constructed of, including materials, sizes of framing, spans, center to center distances, etc - is that info available to you? If so, let's see what you have to work with. If not, you'll likely need an engineer on this one... Steve
PD
Posts: 10
Joined: Thu Jun 17, 2004 5:09 am
Location: San Francisco

Post by PD »

Steve-

Point well taken. I have a friend who works for the city and is getting info on the construction of these houses (maybe even plans!), which, for the most part in this several-block area, were all built by one developer, all around 1920. They seem to be built fairly well, but I need more details for areas I can't eyeball. Most of the homes up and down these blocks are the same exact plan, with small variations on each one.

I do know that these homes were built when 2x4's were 2" wide. By removing the central heat intake vent cover in the corner of this room, I can tell a pretty fair amount: it is clearly a 1/4" oak flooring (not 3/4" :evil: ), sitting on exactly 7/8" thick solid pine planking (total 1-1/8" for the floor leaf), on joists that are exactly 2" wide by 9-1/2" deep and on 16" centers. The joists run perpendicular to the long sides of this room. No details beyond that, at this point, as far as the joist spans, or anything about the beam structure..

I may have to visit a coupla neighbors' garages to see the the first floor beam/joist structure (all bottom floors of the houses with this plan consist of the garage/storage area), because the beam/joist structure of this one is all covered up with sheetrock ceilings throughout the entire garage level, including the mother-in-law apartment, part of which is directly below this room. There are various walls down there underneath this room. One major wall down there divides this room lengthwise into two (roughly 8-1/2-foot-wide and 4-1/2-foot-wide) sections over the 15'-6" length). I don't know yet to what extent (if any) that any of these are load-bearing walls, however.

Hey I'm with ya on that lbs/sq-in deal- I'll never forget the first time I saw what spiked heels did to a cheap vinyl floor. I do know that the previous folks who lived here had a grand piano in this room. Now there's a lot of pressure on those three little wheels..

Any advice possible on the floating floor idea with this level of data so far? If it's more of a psi issue, perhaps I could just build up the present floor with more layers, including a layer or two of Sheetblock or something similar?

Thanks again
Perry
knightfly
Senior Member
Posts: 6976
Joined: Sun Mar 16, 2003 11:11 am
Location: West Coast, USA

Post by knightfly »

"Any advice possible on the floating floor idea with this level of data so far?" -

Yeah, first thing to do is go buy a GOOD stud scanner - I use the Zircon Contractor, the Multi scanner pro model. It has a deep scan feature that works better on thicker walls/floors - you'll want to locate each and every joist on your floor EXACTLY before you start floating a floor, because you'll want the EPDM rubber (don't use neoprene) pucks to be set EXACTLY coincident with your old floor joists so the floated floor gets the best support it can. Home Depot carries that model in Oregon, hopefully there too.

You will still be able to go with 24" centers on your floor most likely, because it's very possible that spacing for proper loading will be adjustable to 48" centers for the pucks, so they would line up with every third joist.

Can't get much beyond that til you find a neighbor that hasn't converted... Steve
PD
Posts: 10
Joined: Thu Jun 17, 2004 5:09 am
Location: San Francisco

Post by PD »

Extremely helpful- thanks, and I'll get on it. Zircon Contractor it is.

I did find out that there is a beam that runs almost down the middle of the room lengthwise, in addition to two more walls underneath, running the same direction, each within 4 feet of this room's walls. I just unloaded all the junk outta this room (it has been the catch-all, full to the brim, since we moved here) and discovered that, unlike the drumlike resonance of the living room, the floor of this room feels much more solid- no rumble when you stomp. Certainly this will not be the data I go on (that'll be the scanner's job), but I feel way better about it knowing it's the most solid feeling and least resonant framed floor in this entire house.

I still want visuals from one of the neighbor's first level as well as the info from the scanner. More when that data comes through.

Thanks very much, Steve.

Perry
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