Working with plaster/wood lath ceiling

[ga-hvac-tech]

May do a project of adding HVAC to an older house with plaster/wood lath walls and ceilings. How would you guys cut holes in the plaster/wood lath for vents, without cracking the plaster and having to repair?

[beshvac]

The best way so far I have found is to get a bunch of titanium drill bits and drill holes all along your lines and then move the drill sideways to connect the holes. Then carefully true up the edges with a sawzall with a titanium blade. Put down plastic.

I have tried diamond blades on skilsaws-about choked to death on the dust and the dust went everywhere.

My contracts say:

• Note on Lath and Plaster ceilings: Installation requires cutting holes in ceilings. We make every effort to prevent cracking around hole locations, but we cannot prevent all cracks or damage to the plaster. Cutting plaster also creates a large amount of fine dust particles, we vacuum as much as possible while cutting-but there will be dust generated. Plaster repair or painting of ceilings not included in contract price

[ga-hvac-tech]

I remember about a year or so ago, I was walking out of HD and saw a guy hawking 'Diablo' sawzall blades (they were a deep red color). He had one with what looked like around 8 or 10 carbide teeth/inch; he said (they all say good stuff...) it would cut plaster/lath.

I did this type of install about a decade ago, remember having to use some sheetrock mud to clean up the mess of cracked plaster.

Anyone have any other suggestions?

[Moonrunner]

Avoiding cracking is dang-near impossible. Some of my experiences as a HO: If you're nice, durabond the cracked area, sand (1/4 sheet palm sander ftw) and then skim over with low dust mud. That's if you really wanna repair all that crap. Otherwise, I'd just sawsall and tell'em to either replaster or just get a drywall guy to do what I suggested. Got some pretty sweet results in a property that was being staged for sale. The kitchen that was done by a good drywall guy was looking REALLY good after a couple of years, the rest of the house was done by a crew of semi-pros, looked alright, but I really wished that the guy who did the kitchen didn't decide to take up trucking lol

[Sleuth]

.
Have plenty of patience saved up for this job.

I use metal cutting blades on cordless skil saw and sawzall. You will powder
the whole place one way or the other.

Spot the boots and draw the outline and get r done. I allow for cutting in
only 3 to 4 boots per day if the house is occupied.

I wear N95 dust respirator, hoodie and glasses. I have a
curtain rod 2 foot square made of 1" PVC that I drape painter's plastic
over and press up against the ceiling with "3rd hand poles" to protect the surrounding(s).
And tie a knot in the bottom of the plastic drape to catch all the crud falling.

The job has to pay really well for me to get involved. I believe it's really
about having plenty of time to do it. It's a job you just don't want to do in a rush.
..

[ga-hvac-tech]

THX a bunch for the replies! I had forgotten how difficult it is to cut vents through a plaster ceiling.

The house is two level; main will be floor vents, upper will be ceiling. It appears around 12 penetrations through the plaster ceiling upstairs will do.

The last time I did this was around 2001 or 2002; I was a lot younger and had more energy... <grin> Yeah, the plaster cracked and a few chunks fell to the floor. If memory is good; I repaired it with sheetrock mud (coule of coats), and the owner painted. Nice thing about plaster walls/ceilings is they are not as 'clean' (smooth with no bumps) as sheetrock with proper joints.

It appears there will be some 'educating' the HO when I present a contract for a significant amount of $$$... They can take it or leave it. If I am going to do this much work, and do it to the usual high quality standard, I will get paid a reasonable amount for it.

[skibme]

I don't miss those days.FYI some plaster had asbestos in it.

[kls-ccc]

We alsways try to mark the holes so at least one if not 2 sides are between lath. Also found that a Rotozip bit in a Dremel works well, just use one for plaster removal and another to cut the lathe.

[Space Racer]

Here's a This Old House technique:
http://www.thisoldhouse.com/toh/how-...860015,00.html

I would score the cutout with a razor knife
before drilling the holes.

[dlove]

May do a project of adding HVAC to an older house with plaster/wood lath walls and ceilings. How would you guys cut holes in the plaster/wood lath for vents, without cracking the plaster and having to repair?

I did a house long ago with plaster walls and ceilings. hole saw corners worked well. sawsall was OK but bulky and if, like in my case, it caught a lath not nailed and jerked. it pulled a good size piece out and formed a crack. The bad thing, this house had a mural on it and i was freaking. luckily it was in the clouds and they were able to fix it. i did tell them i couldn't guarantee something like this wouldn't happen, but you still sweat it. Looking back and with a better section of tools we have today. I would Hole saw the corners 1" or 1:1/2- fine tooth- and use a 3 in. Mini Circular Saw to make the straight cuts. like this http://www.sears.com/craftsman-10872...2&blockType=G2

dremel i think makes a small saw. look for a battery operated one no cords, easy to work with

A sawsall is to unpredictable and if you need to shave the side a sawsall will butcher it. At least with a saw you and shave. Also, you can mask tape over where you will cut that will help with chipping and not making the ceiling or wall up.

[southshorejohn]

Oscillating Multifunction Power Tool from of all places Harbor Freight and on sale now for 23 bucks. I live and work in the Boston area and needless to say we have a lot of plaster around here. I use this tool for these type cuts all the time, does a good job, spray with a little water first for dust control.
P.S. Look at all the different blades that are available.

[ga-hvac-tech]

Oscillating Multifunction Power Tool from of all places Harbor Freight and on sale now for 23 bucks. I live and work in the Boston area and needless to say we have a lot of plaster around here. I use this tool for these type cuts all the time, does a good job, spray with a little water first for dust control.
P.S. Look at all the different blades that are available.

Now THIS looks like an idea! I used one a few times to cut out tall base for a return filter-grill... works a lot better than a sawzall.

I also like the idea of squirting a little water (misting bottle) on the cut line before starting... should help with dust.

THX again guys for all the great tips!

GA

BTW: Like your avatar... Is it safe to be around you now... <grin>

[Rcb2875]

May do a project of adding HVAC to an older house with plaster/wood lath walls and ceilings. How would you guys cut holes in the plaster/wood lath for vents, without cracking the plaster and having to repair?

A friend of mine used a rotozip when he was working on his house. I think he used a dura bit or something. Said it worked pretty well and didn't shake the hell out of the walls and ceilings like the sawzall did.