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-   -   Drywall Over Plaster Lath (https://www.contractortalk.com/f49/drywall-over-plaster-lath-115572/)

oldhouses 03-26-2012 07:27 PM

Drywall Over Plaster Lath
 
Hello,

I'm working on a 100 old house with a flat roof. Top floor ceilings are plaster lath construction, with true 2x4 framing and loose fill above. I would like to add 1x3 furring strips to level and then 1/2 inch drywall, but i'm concerned about the extra weight..... Taking plaster and lath down, is not an option.... Any suggestions will be appreciated.

Thanks

schaefercs 03-26-2012 09:00 PM

What about just taking the plaster down not the lath?

cleveman 03-26-2012 09:05 PM

Why is it not an option to remove the plaster & lathe?

If it is not an option, why are you posting?

ohiohomedoctor 03-26-2012 09:10 PM

I am assuming is not an option is code for "possibly over your head" or perhaps "more than you want to bite off". The best case is always to remove old wall board so that a proper inspection can be preformed. Also gives you an option to update electrical and install proper insulation all while reducing total weight load on the structure. Maybe you (original poster aka op) could elaborate on why removal is not an option so that more clear and specific advise may be given.

Tinstaafl 03-26-2012 09:25 PM

It's not all that uncommon to drywall over old plaster & lathe vs the labor and mess associated with removing it. In most cases, you can use 3/8" board instead of 1/2" if you're concerned about the weight. Those old 2x4s can take a lot more than the modern stuff.

ohiohomedoctor 03-26-2012 09:31 PM

Quote:

Originally Posted by oldhouses
Hello,

I would like to add 1x3 furring strips to level.

Thanks

This is the part that struck me. Not sure how much leveling this is going to accomplish. Also, tins was right, typically when this is done its 3/8 over top no furring to minimize jamb and electrical box extension work.

hdavis 03-26-2012 09:49 PM

Rocking over plaster and lath is very common, as is busting out the plaster, leaving the lath, and rocking. FWIW, as an RRP certified professional, I can tell you that yanking out the ceiling definitely would require the whole lead treatment routine and possibly may have to be treated as asbestos containing. In any event, you can easily rock over a ceiling while the rest of the house is occupied. Take out the ceiling and you just signed up for another inspection and so on and so forth. A lot of the old plaster ceilings were strapped down with 1X3 furring and lightweight tiles similar to Homasote installed. It's pretty common to see these installations pulling loose, but they usually don't fall down. Wallboard, on the otherhand has plenty of weight to pull the strapping the lath is nailed to right off the joists.

hdavis 03-26-2012 10:06 PM

Quote:

Originally Posted by ohiohomedoctor (Post 1463248)
This is the part that struck me. Not sure how much leveling this is going to accomplish. Also, tins was right, typically when this is done its 3/8 over top no furring to minimize jamb and electrical box extension work.

I've seen this done (and disagree with it). Shims are placed between the 1X3 and the ceiling to level it.

I also disagree with just screwing 3/8 onto the existing plaster. You're basically doubling the weight that's being held up by the few nails put in 100 years ago that tie the joists and the original strapping. There was one around here that made the news when it fell down on people.

When I do these I use 2X4s for strapping and put them directly below the joists. 4 screws are put into the joists through the new strapping at each of the intersections of original strapping and joists just beyond the edge of the original strapping. I just have to make sure there is no wiring in the way before I put the screws in. If I want to shim, I have to pull the ceiling back into place first, then shim and strap.

Maybe it's overkill, but it won't fall down.

ohiohomedoctor 03-26-2012 10:10 PM

I understand the rrp restraints, the additional inspection, and added costs involved, but at the end on the day there is simply not substitute for stripping it down, adding new lighting and insulation, and getting a chance to see the structure first hand.

Big Shoe 03-27-2012 05:29 AM

I would go with metal hat channel. No worrys about wood splitting and it is very easy to shimm.
Definitely find trusses to screw into.
As far as drywall, the added weight issue is interesting. I normally only double up with 1/2''. But I don't think 3/8' would be an issue with the channels 16'' o.c.
I rarely run into plaster remodels here.

Frankawitz 03-27-2012 08:37 AM

This always gets me drywallers trying to fix plaster:rolleyes:
Why not take the time to learn how to fix the plaster instead of tearing it out or covering it up. Oh yeah I know if takes to long and costs to much,!

oldhouses 03-27-2012 08:43 AM

As hdavis spoke about, I'm trying to avoid the possible lead/asbestos issue and still be safe.... This is why I was asking about the original true 2x4 construction.... My spans are 9ft in one room and 15ft in the other, and as I mentioned before, I was thinking about the added weight of the sheetrock... The structure is slight pitch flat roof supported by 4x10 true lumber and 24 inch of attic space with loose fill over true 2x4 lumber about 40ft long 16 oc covered with original plaster/lath.... I would say in decent shape for being 100 years old wihout sag.... I would like to just rock it and encapsulate everything...

I was also thinking about reframing new ceiling below... I have the height because the ceilings are now 12ft tall... I figured I would have to use 1x6 and 1x8 lumber....

Chris G 03-27-2012 09:09 AM

Oh heck, if you've got 12 feet, then reframe it like a drop ceiling. I know you think the joist haven't sagged, but I'm sure they have. Shimming furring strips on wonky plaster can drive a gentle man to kill kittens.

hdavis 03-27-2012 10:42 AM

Quote:

Originally Posted by ohiohomedoctor (Post 1463309)
I understand the rrp restraints, the additional inspection, and added costs involved, but at the end on the day there is simply not substitute for stripping it down, adding new lighting and insulation, and getting a chance to see the structure first hand.

I agree. In this case, he's going to be forced to remove the insulation and inspect the joists and original strapping/ lath from above, or he won't know where to put the screws.

I'm somewhat grateful when someone in the past strapped down and left the original plaster ceiling, it gives me a chance to restore the original ceiling. Even better are the Armstrong dropped ceilings. Ugly, but lot of times I find original crown mold still in place.

Tinstaafl 03-27-2012 10:48 AM

Quote:

Originally Posted by hdavis (Post 1463551)
In this case, he's going to be forced to remove the insulation and inspect the joists and original strapping/ lath from above, or he won't know where to put the screws.

:blink:

A few pokes with an 8D nail will locate a joist, and from there it's once or twice per joist just to confirm whether they're uniformly on center across the span.

Still way faster and cleaner than stripping everything.

aptpupil 03-27-2012 11:10 AM

i usually opt for repair. big wally's plaster repair followed by mesh sheeting over the entire cracking surface and skim coat. for me it's better than rerocking and all that goes into that.
i've yet to come across plaster that is so messed up that this method hasn't been sufficient, but i'm sure there are instances where that is the case. pictures might help.

hdavis 03-27-2012 11:27 AM

Quote:

Originally Posted by Tinstaafl (Post 1463555)
:blink:

A few pokes with an 8D nail will locate a joist, and from there it's once or twice per joist just to confirm whether they're uniformly on center across the span.

Still way faster and cleaner than stripping everything.

The way I do it, you have to know locations of both the joists and original strapping. I put 4 screws into the joists just to the outside of the original strapping. It takes awhile to find these probing through the ceiling, even if you're just doing the edges and mid span for each. He also needs to know he's not going to be putting a screw through a wire. If it were a ceiling between the first and second floor, I'd locate everything with a stud finder, nail and a NCV probe, and cut some small holes for any areas I have questions about, but this guy has access from the top Maybe I'm a little too careful, but I've done a bunch of these.

hdavis 03-27-2012 11:38 AM

Quote:

Originally Posted by aptpupil (Post 1463562)
i usually opt for repair. big wally's plaster repair followed by mesh sheeting over the entire cracking surface and skim coat. for me it's better than rerocking and all that goes into that.
i've yet to come across plaster that is so messed up that this method hasn't been sufficient, but i'm sure there are instances where that is the case. pictures might help.


I there is crown mold in place, I almost always do plaster repair. Putting 300 plaster buttons into a 120 sq ft ceiling because the keys have popped off takes a little time, and you can't exactly skim it. If it's just a cracking issue it's much faster to do a repair. My next job probably has some ceilings I'll have to take the plaster off of a ceiling or two - I'll see about posting when I get started.

oldhouses 03-27-2012 03:58 PM

no crown molding.. So, i could install plaster washers and skim, but I still like the idea of sheetrock over the plaster and not playing with the possible lead and asbestos issues of removing and possible future cracks of the skim coat.... Has anyone installed new sheetrock over an original plaster lath ceiling with true 2x4 framing??

Tinstaafl 03-27-2012 04:22 PM

Quote:

Originally Posted by oldhouses (Post 1463646)
Has anyone installed new sheetrock over an original plaster lath ceiling with true 2x4 framing??

Yes, and without issue. However, those I've done didn't have the strapping hdavis refers to. Probably a regional thing.


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