It's snowing in Miami in February and I am snowman! Cutting plastered walls

[MiamiCuse]

I posted an inquiry a few weeks ago about cutting old plastered wall that is has af gypsum lath as a double layer wall board.

I need to cut small holes on these existing walls for electrical outlets, intercom units, and also old demolished walls that have unclean tearouts at corners that have embedded wire meshes. Initially I tried to use a recipricating saw, no luck, then tried a rotaty tool and that worked fine for like 5 minutes, then today I tried an angle grinder and it worked.

I knew it would be dusty, so I prepared and worn an extra layer of clothing, I put on a cap, a twin catridge respiratory mask, a eye protecting mask and went to work. It was DUSTY. When I cut the corner joints at the ceiling there were so much dust flying it's like snowing right into my face. I forged ahead and kept going. Soon I can't see the chalk lines I drew because it was so dusty. I opened the doors and the dust started to float outdoors and it does not settle, it seems to float up.

I took my mask off and it has dust inside the mask, which was unexpected since I was wearing it very tight. Next I have this gritty taste in my mouth, did the dust get inside the respirator? I looked at myself and I am like snowman. I had some of this dust in my hand and it didn't feel like dust it's like silt and it's all over me. I am starting to worry...does plaster (built in 1972) have asbestos? It seems to have gotten inside every of my pore, I mean, I was wearing long pants outside and shorts inside, and I had my cell phone inside my short back pocket. When I cleaned up and took out my phone, I flipped it open and it opened half way, dust got inside the hinge and clogged it! How does it get past two layers of clothing?

I am only half done, after doing this for about six hours, but I am hesitating to go forward without knowing more about this dusty silt and if it could be a health hazard. Is there a mask that can protect against this?

Thanks,

MC

[hallerb]

at the ceiling

..does

MIGHT have asbestos in it......

personally if i am making a big hole in a plastered wall i use a hammer, and occasionally a chisel.

sawzall or jig saw tends to loosen plaster from wallboard and makes tons of dust.

this advice does not apply to lathe and plaster

[Robert Allison]

I very much doubt that there is asbestos and even if there was, long term exposure is the problem with that. Of course, none is better, but I wouldn't worry about it unless you plan to do this on a regular basis for the next few years.

The mortar does have silica, which is a known hazard, but this is also a long term exposure problem rather than just a one time danger. If you don't plan on doing this for an extended period of time (years), then you don't have anything to worry about except for (excuse my vulgarity here) strangely white boogers.

You have discovered the joys of cutting concrete! Be thankful. You won't have to stay up nights wondering anymore! Horrible, isn't it? You will be finding this in cracks and crevices for a long time. It is a very fine dust almost like talc.

A common particle mask is ok for this type of dust. A respirator is fine, too, but probably overkill. If you have to do any more, then take your shop vac and hold the nozzle so that it sucks up the dust as you cut. Makes an amazing amount of difference and you will not have so many problems with dust. You may have to clean the filter on your shop vac more than usual.

Be warned that this type of dust is the absolute WORST for electric tools. It is abrasive and gets into the windings and gears and bushings, etc. We always have a lesser quality grinder or saw to do this work with and we clean it with a high pressure air hose after use. (Start the grinder and then blow out every crevice that you can find until dust stops blowing out.)

Good luck and don't worry.

[Richard J Kinch]

Plaster and gypsum board in those days commonly used asbestos.

I wouldn't worry about a few short exposures, although fine dusty fibers are exactly what you should worry about if anything. Get a respirator that fits, and wet wash everything.

[RicodJour]

You need to learn some dust control measures. When cutting anything like concrete/drywall/plaster indoors, erect some temporary barriers to close off an area. Plastic or drop cloths work well and they should fit fairly tightly to the walls, floor and ceiling. You should pick up most of the dust at the source, so tape a vacuum hose to the tool or have someone hold it right next to the cut as you work. Having a long hose, and the vacuum outside so the vacuum outlet is not blowing stuff around is optimal. Just as critical is to rig up a fan in a window or doorway blowing out. Close off around the fan with cardboard so air turbulence won't bring the dust right back in. You can tell if you've set up your protection correctly if the plastic bulges towards the fan when you turn it on.

R

[MiamiCuse]

RicodJour,

I am basically doing cuts around the entire house so there is no need to tape off or block off any specific areas.

I feel bad about having someone holding the hose next to it. 60% of the cuts are actually above the shoulder heights some in the ceiling so it is really difficult to get someone to be on a ladder next to you holding a hose that high anyways I thought I would just "tough it out" but boy I did not know it could be SO dusty.

The thing that really is challenging is that the dusty blurr up the eye protector so fast that while it's cutting it's hard to see the chalk line I scored.

The other problem I have is the plastered has metal wire meshes in it but only around inside corners. When I cut that I am getting sparks from the grinding wheel going across and I had to go real slow. I am concerned may be I could be cutting an EMT pipe, or a AC condensation pipe or other hidden metallic things, probably not but I don't like the flying sparks.

I am also predicting where my electricians will need cut outs and doing them in advance, as I will not let them pound a big irregular hole in my wall and celing anymore. Now I have an irregular size holes in the ceiling, in some cases wider than the knock out circle size of the hi-hats, I am not sure what to do with that, I don't have a hole saw that could cut this plastered wall in perfect circle, and the holes may be wider than the needed circles. I can't patch half an inch of an irregular sliver the remodel light fixture needs to "clip" onto something. I think my only choice is to go to every wrongly cut hole in the ceiling and cut a 16"x16" square hole, then put in

5/8 "normal" sheetrock and recut the circle?

Thanks!

[Roger Shoaf]

The person holding the vacuum does not have to be on a ladder. They can use a length of plastic pipe secured to the hose and stand on the floor.

Vacuuming as you go will solve this problem also.

You might consider using one of those roto zip tools. The carbide cutter will cut through the metal lath, and they sell a dust extractor that connects directly to your shop vac. See

As far as hitting pipes or wires in the wall this is not likely as they tend to be located in the center of the stud, well back from the inside of the plaster.

How much bigger did you cut your holes? If it is just a bit the trim should cover, but if you are way over then you might want to just patch the oops. Several ways would work First you have a large hole in your ceiling so you can insert some sort of bracing to hold a fabricated wood backing to support a patch made from drywall compound.

The other way would be to make a plug that is the size of your desired hole and wrap it with polyethylene. Now you can fill the void with new plaster, and when it is set knock out the plug and peel away the plastic leaving the correct size hole. Styrofoam might work here also.

The key to patching plaster is to remove any crumbling around the edges otherwise the patch will fail.

You also might want to avoid sharp inside corners when you cut a hole. A rounded corner is less likely to be the start of a crack than a square one.

[MiamiCuse]

I am going to try the rotozip tool with the plaster bit and see, I think it will give me better maneuvering in corners. I have to get an industrial model right?

I have a dremel right now and I know they have a drywall bit, but I think for what I am doing the dremel is too light weight and probably will clog up in 10 seconds.

MC