Pressure Washing Interior Brick
We’re renovating an 1880’s carriage house in Williamsburg and we need to clean the interior walls prior to repointing. Our contractor suggested a 2-stage pressure wash, first pass with muriatic acid, followed by a water rinse. Does this sound like a good plan? We’re worried about acid damaging the old unfinished wood floors and beams.
We’re renovating an 1880’s carriage house in Williamsburg and we need to clean the interior walls prior to repointing. Our contractor suggested a 2-stage pressure wash, first pass with muriatic acid, followed by a water rinse. Does this sound like a good plan? We’re worried about acid damaging the old unfinished wood floors and beams.
Here’s what happened: our contractor promised to do a very gentle wash ( I sent him the link to the restoration website) and we are very pleased with the results. As sxm mentioned, the brick is much ‘brighter’.
It came out so well that we’ve decided to forgo any further work on the walls except for sealing -which is thankfully saving us a few $$$.
The wood beamed ceiling and plank floors also benefited from the wash. Fortunately with the recent dry weather and the fact that we have no windows (the masons are working on the openings) the entire place dried out pretty fast.
This was definitely one of those situations where we just had to grit our teeth, go ahead and hope for the best – sometimes renovation takes nerves of steel. We were lucky this time.
Thanks again for all your intelligent input.
Having just spent 2 weekends cleaning and pressure washing my deck, I really can’t imagine wanting to use a pressure washer inside the house — even if it’s all ripped apart and undergoing a renovation. The amount of water involved is huge.
Well, yes, the grinder smooths the brick, but because it is taking off a very thin layer of brick, mostly grime and dirt, the smoothness will be consistent throughout your brick wall.
I mean, you are using it as an interior wall, and people will be touching it, leaning on it, etc, so wouldn’t you want it smooth w/ no masonry cement mortar sticking out and scraping you?
I have found that the muriatic acid cleans and brightens the brick. The acid really cleans little tiny pores of the brick and gets rid of all the dust from the grinding. Just getting rid of all that dust really brightens the color. The texture after the acid, makes it feel like a very matte, soft, porous, interior brick.
If you apply silicone afterward (diluted of course), you will feel slightly more resistance, small rubbery feeling when running your finger over the brick, but will still feel the graininess character of the brick. But I guess that depends on how much silicone you apply.
sxm- I’ve tried using the angle grinder with the wire brush cup and it gives the brick a smooth texture as well as discoloring. Does the muriatic acid affect the brick texture and color?
i dont understand why they are saying to clean before the pointing? all pointing (unless repointing all walls) will leave inconsistencies that vary from texture to color.
I say repoint where needed, then grind down all the dirty old brick and pointing to a uniform color/consistancy. Most interior brick walls were suppose to never be seen, so most of the time, the brick and mortar is very rough. We’ve used a big angle grinder with wire steel cup brushes.
Then clean with muriatic acid, rinse, all the while protecting the floors, whether they are old, new or even just subfloor. Seal the brick with your favorite sealer or silicone (which we use).
Sand/grit blasting sounds good, and fast, but interior brick is old and soft, so be careful
Its a carriage house – the one-time (or two-time) deluge of water probably won’t hurt anything, assuming nothing has been built out below. In other words, if the building is wood framing carrying wood flooring with no plaster, drywall, finishes, etc. etc., it will not damage anything and dry out pretty quickly (well, assuming anything dries out after our recent weather).
Muriatic acid (hydrochloric acid, HCl) is a standard masonry cleaner. You can also use specialty masonry cleaners (Sure Klean by ProSoCo, many others), but these too tend to be HCl based (some are hydroflouric acid, HFl). In ALL cases, the cleaner should be used at a proper dilution, not at full strength. The dilution, combined with the large amount of water that goes into the pressure washing dilutes a lot of the toxicity/badness/etc. However, you should also check laws on disposal – often it is not legal to simply drop this into the drain.
You can do a lot more damage to your brick (and mortar) with a pressure washer than with HCl, especially if it is an older (pre-20th century) and especially, especially if you are cleaning the interior of a party wall. You should test to make sure that the cleaning will not erode the mortar joints or brick unduly.
Another alternative is grit blasting. Before any preservationists cringe, grit blasting is an allowable treatment under NPS guidelines, provided it is for the interior of industrial or manufacturing buildings. A carriage house interior may qualify. There are all sorts of grit systems out there, from very low-pressure organics (walnut shells, for instance) to sand or other abrasives. It will erode some brick surface (which is why NPS only approves it for interior work), and you want to stay away from very aggressive grits (black beauty, e.g.) and very high pressures.
Last, if the walls are painted, be VERY careful how you remove. Quite likely there is lead there, and grit blasting or washing can move that lead everywhere.
OP: Would sooner tape tarp or plastic + rosin paper than ever push water through floors to who knows what and where. Water travelling through existing structures is one case where the law of gravity does NOT reign supreme (but some law far more worrisome than Murphy’s does). Especially would not use this strategy if water contains contaminants, corrosives and/or toxins like muriatic acid.
@tybur6: The floors are very old with generous gaps between the planks. On the upper floors we’re going to use brooms to push the water through the cracks down to the cellar where we can sweep it into the (filtered) floor drain.
@vinca: Thank you very much for the extremely helpful link! It convinced us to try cleaning the masonry with water only – gentle is the best way to start, especially interior.
@Adam: You’ll kill yourself with a wire brush! I know from experience. I’ve seen the peel away products used on exteriors and they seem to work very well, but I don’t know the specific brand. Good luck!
I also am looking to remove old paint and caulking from exposed brick and have been looking for some help to get it off as well. I tried using one of those wire brushes and it turned the brick a metalic color as well as tiring the hell out of my arm.
Would any of the peel away products be good? What you guys recommend?