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-   -   Question Re. Parging Over Brick (http://www.diychatroom.com/f19/question-re-parging-over-brick-73959/)

Captain.Sassy 06-17-2010 11:26 AM

Question Re. Parging Over Brick
 
Hi guys!

I've got a question for anyone out there who is familiar with brick work and masonry etc.

I have a porch outside of my house which has concrete steps (over a wood frame) and has a pillar which partially supports a balcony above it. The house is a semi-detached, so the balcony is supported by the pillar on my side and a twin pillar on my neighbour's side of the porch.

Anyways, the previous owners of the home put tile all over my side of the porch. I tore the tile up, and found that under the tile on the pillar was some old brick. The house is a fairly old house (late 1800's or early 1900's) and so the brick is of the softer type.

The brick was in terrible shape, with a lot of spalling and the mortar falling out if I pushed it with my finger. On the inside of the porch however (there is a little door that gives access to the underside of the porch) the brick is in much better shape, and so is the mortar. My buddy (who does some brick work) said that this was likely the result of the brick not being allowed to 'breathe' as the tiles make a very airtight seal over the brick.

After I repointed the brick and replaced some of the really bad bricks (i.e. those that were cracked right down the middle or had spalled in really significantly) I decided that I would parge over top of the brick surface to make the pillar look nice. However, when I went to a specialty masonry store, the guy there advised against parging over the brick, since he said that this would again seal off the brick and lead to further deterioration of the brick, just as the tiling had.

So I devised a solution which I was hoping would let the brick 'breathe' while getting a parging surface over top of the brick.

My plan is to first put some roofing paper over the brick, then take strips of 1X2 and use tapcons to fasten them running along from the top to the bottom of the brick pillar. The pillar is 17" by 17", and I'm planning on running three strips of 1X2 along each face of the pillar. (It's a rectangular pillar). After running these strips of wood along the face of the pillar, I'm planning to use poultry staples to affix metal lathing to the wood, and then parge over the lathing. This will, I'm hoping, leave a little air between the brick and the parge so the brick can breathe. I know that the parging over the lathing between the wooden rails will be fairly weak (i.e. can crack if pressure is applied to it etc.) but I figure this is probably still better than the alternative of letting the brick deteriorate further.

Any thoughts would be appreciated.

Your pal,

Captain.Sassy

stadry 06-18-2010 06:17 AM

if i'm reading your post correctly, wire mesh the column & parge away,,, the brick's probably deteriorated because it couldn't breathe + it was subject to freeze/thaw damage from water penetrating the tile - NEVER a good idea UNLESS you're in mexico or anyplace where it NEVER gets below 34f imn-s-hfo :thumbsup:

next time just clean the brick & apply 2 coats of silicone siloxane sealer,,, btw, picture or 2 wouldda been a huge aid :yes:

Captain.Sassy 06-18-2010 09:18 AM

Thanks for the reply itstreallyconc, appreciate the input.

The silicone sealer lets the brick breathe? Or does it just keep out the moisture? Would have to pull the whole porch apart to get at *all* the bricks and apply sealer, instead of just the exposed face?

Anyways, here are some scientific diagrams of what I plan to do:
http://img404.imageshack.us/gal.php?g=crosssection.png

(I didn't bother to resize the pics, so if you just click on the link you'll bring up the steps to my scheme. The last pic shows the cross section and indicates where the air space will be.)

Cheers,
CS

jomama45 06-18-2010 11:24 AM

I'm with IRC on this one. Anchor galvaized lath directly to brick & plaster it out, using mostly lime in the mortar. Let it sit for a few weeks and seal with a siloxane or even a somewhat breathable paint if you want.

And, an actual picure, as well as the climate in your area, would still help.

Captain.Sassy 06-18-2010 11:50 AM

I can't do much about an actual picture right now since I'm at the office.

I'm in Ottawa; we have cold, dry winters and hot, humid summers. R

Captain.Sassy 06-20-2010 08:30 AM

Well I screwed up. I did the parging in type S, which I thought was lime based. Then I looked it up and found out it's cement based.

I'll leave it as is for a year, but next summer I guess I'll tear down the lathing and re-do it with lime based mortar that I'll mix myself.

Thanks for the suggestions guys.

CS

NJ Brickie 06-20-2010 03:17 PM

Nothing wrong with using a type s mortar. You did nail lath to the brick? Type S is 1 part portland cement, 1/2 part lime, 4 1/2 parts sand

Captain.Sassy 06-20-2010 03:45 PM

I didn't use nails, I used 3/16" tapcons with washers to anchor the lathe.

Type S is okay then? I figured it wouldn't let the brick breathe enough since it's not as permeable as a mortar with a higher lime content.

NJ Brickie 06-20-2010 04:14 PM

You had two options at the start. A breathable system or seal it off. If you wanted it to breathe you could have used a Type K mortar. Since you now have a Type S on there you have gone the seal it off direction. As long as water is not getting to the brick you will be fine. Are there areas that you did not seal off? As long as the lath was secured well and you have a decent thickness of parging (atleast 1/2") on there you will be ok. I would also buy a quality masonry paint and paint it.

Captain.Sassy 06-21-2010 08:09 AM

No, all the exposed faces are parged over now. The inside of the porch is still exposed, but it keeps pretty dry it seems.

Should I then seal around the seams i.e. caulk around the edges of the parging? Someone told me something about caulking around window sills between the sill and the brick after repointing to keep water out.

Thanks for the tips!

stadry 06-21-2010 08:18 AM

we wouldn't use caulk as its got a short life expectancy,,, instead we'd use polyurethane, polysulfide, or 100% silicone - ALL w/closed-cell backer rod in the proper size reservoir

jomama45 06-21-2010 09:39 AM

This should last a fairly long time the way you did it. There is the chance that water may wick up from the groung though.

A picture of the actual situation would still be easier for me to understand exactly what you have going on though.

Captain.Sassy 06-21-2010 09:43 AM

Quote:

Originally Posted by itsreallyconc (Post 459241)
we wouldn't use caulk as its got a short life expectancy,,, instead we'd use polyurethane, polysulfide, or 100% silicone - ALL w/closed-cell backer rod in the proper size reservoir


http://www.homedepot.ca/wcsstore/Hom...8cd24aec_4.jpg

/\/\/\
Is this the stuff I want, i.e. GE 100% Silicone for Door and Window?

Also, what does the backer rod do? I'll have to chip out some of the scratch coat to fit one in. (Was planning to do the second coat tonight).

Cheers,
CS

Captain.Sassy 06-21-2010 09:48 AM

Quote:

Originally Posted by jomama45 (Post 459272)
This should last a fairly long time the way you did it. There is the chance that water may wick up from the groung though.

A picture of the actual situation would still be easier for me to understand exactly what you have going on though.

I'll throw up a photo or two tonight!

stadry 06-21-2010 10:56 AM

rather see tubes from any const supply house for dow/corning type m silicone ( ' m ' means you have to ' tool ' the sealant ) ' tooling ' forces the mtl into the substrate jnt faces & provides better adhesion,,, ' sl ' is self-leveling & we wouldn't pick it,,, backer rod provides shape factor,,, jnt sealants are designed for 2-sided adhesion, NOT 3


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