Cleaning Limestone Walls

Bill in Austin

New member
Hello there,

I'm new to the forum, so...

Question:
What methods/products do you use to clean limestone sided houses?

This part of Texas is dirty (pun intended) with limestone exteriors, yet I cannot find videos or discussions about cleaning them. I find lots about cleaning vinyl siding but.... not limestone.

As a homeowner (not pro washer) I've tried a couple of commercially available house washes, used them as directed and was disappointed with the results.

I went back to my tried and trusted SH mix, along with general, light power washing and was please with the results. The true soft wash method removed very little green and black mold, it took power washing to get most of it out. I would say that with all the rain we've had in Central Texas this year, the black mold is deep in the porous limestone.

Do you know of any other method or product to remove the deep black mold?

Also, since limestone is so porous and with the current heat we're experiencing, I'm having a hard time keeping the stone whetted while working, the SH and soap mix I use seems to soak in within seconds. Would a commercially available surfacant work better than common dish soap for this application?

Would an algecide topical post-application be recommended for the limestone walls? If so, what are some reputable products to test?

Thank you for your time, Bill, Austin, TX
 
Well since I've had no replies, I suspect my questions are either too basic for this forum or its not worth the trouble to respond.

Let me take another approach..... here's what I think (from looking at multiple sites, forums and posts) is the way to handle my conundrum:

Pre-wet (soak well) the wall and vegetation.
Use a house wash of 12.5% SH / water /surfactant (ratio: 1 gal / 2 gal / 2-4 oz depending on product ???) (ratio: 3 gal / 2 gal / 2-4 oz ???)
Apply with DS injector (I don't have X-Jet or dedicated low pressure pump system.)
Dwell time 5-15 minutes depending on conditions and mixture ratios.
Keep wall wet, (with more product or gentle water spray?) This is tough to do as the limestone is so porous and heat in central Texas is usually in the 90's.
Flush wall with water to rinse house wash off, trying to leave no house wash residue.
Repeat as necessary to get the black mold out of the rock.
Use pressure as a last resort to "scrub" out mold.

A few comments from previous efforts:
A strong SH mix has proven effected but has basically bleached out most the rock's natural color variations.
Strong pressure cleans the mold (generally) but at the cost of removing rock material. Small chunks and grit come flying off.
The limestone seems to be more susceptible to the next mold "infestation".

Comments, suggestions and guidance are requested.
 
Doug Ruckers Been out of town on a huge Softwash cleaning project
Hello there,

I'm new to the forum, so...

Question:
What methods/products do you use to clean limestone sided houses?

This part of Texas is dirty (pun intended) with limestone exteriors, yet I cannot find videos or discussions about cleaning them. I find lots about cleaning vinyl siding but.... not limestone.

As a homeowner (not pro washer) I've tried a couple of commercially available house washes, used them as directed and was disappointed with the results.

I went back to my tried and trusted SH mix, along with general, light power washing and was please with the results. The true soft wash method removed very little green and black mold, it took power washing to get most of it out. I would say that with all the rain we've had in Central Texas this year, the black mold is deep in the porous limestone.

Do you know of any other method or product to remove the deep black mold?

Also, since limestone is so porous and with the current heat we're experiencing, I'm having a hard time keeping the stone whetted while working, the SH and soap mix I use seems to soak in within seconds. Would a commercially available surfacant work better than common dish soap for this application?

Would an algecide topical post-application be recommended for the limestone walls? If so, what are some reputable products to test?

Thank you for your time, Bill, Austin, TX
 
Alright folks, 128 views and no guidance.....

I understand your reluctance to give a "homeowner" help, but I'm in the process of discovery for starting up a business here in Central Texas and need basic info to try on my own house before spending more money going to class (Houston).

I just received a chemical sample kit from Pressure Tek and am eager to try them. I currently am under GPM'd (3.6 gpm, 3600 psi) but it's what I have.

My primary market is limestone sided houses, concrete/exposed aggregate drives and walkways. The info I have seen on the web is NOT geared to limestone sided houses. Throw me bone here....

Sincerely, Bill in Austin
 
For limestone we use a bleach mixture applied with a dedicated pump. You could try downstreaming, but depending on how and it is may not be strong enough.
 
Thank you for your reply. I would be downstreaming a 12.5% mixture, with water and Elemonator. I just installed an Adams adjustable injector and need to test it's flow rate with my pump and hose combo. Would the 3 : 2 (SH : water) ratio be a good starting point?
 
Thank you for your reply. I would be downstreaming a 12.5% mixture, with water and Elemonator. I just installed an Adams adjustable injector and need to test it's flow rate with my pump and hose combo. Would the 3 : 2 (SH : water) ratio be a good starting point?

Really hard to answer not knowing how bad it is but all you can do is try it. We never downstream on limestone cause it usually isn't strong enough a mix....
 
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