Crack Monitors and Adhesives 1

[Craig_H]

I have been contacted by a local church regarding cracks in the brick veneer of their building. The structure was built in 1925 and is a wood framed church with 4" brick veneer, sitting on a 10" thick concrete foundation wall. Cracks predominantly appear above basement window openings and continue into the stone veneer on the foundation. I suspect that these cracks above windows are old and are not moving, but want to monitor the cracks especially through the spring thaw to confirm that suspicion.

The crack locations are located in prominent areas visible from the street. Most crack monitors on the market recommend epoxy adhesive as a preferred method of install, which is not tolerable in this situation. Has anyone successfully used anything easier to remove to fasten crack monitors? I was picturing something along the lines of a butyl tape or other similarly sticky adhesive that would be removable without visibly damaging the brick veneer. Humboldt Manufacturing was somewhat helpful, indicating that a two-sided tape may work if adequately protected from the weather.

 

[XR250]

What about hot glue?

 

[GeorgeTheCivilEngineer]

Screw hole into mortar joints?

 

[dik]

Is the cracking confined to the mortar joints? What is the brick type? It may be a matter of repointing, using a proper 'low strength' mortar, not a PCC based mortar. I would not use a glue gun. Try patching an area out of the 'main stream' to see what the effects of patching are. Often patches are worse than the original damage.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Craig_H]

Dik, cracking is confined to mortar joints. Indeed, I am aware of the need to match the mortar appropriately. There is some evidence of minor repointing having been done with a portland cement mortar and I made the owner aware of the need to source an appropriate contractor for future repointing. What's your reason for avoiding a glue gun?

George, that may be an option, but would only allow for two out of four specified fasteners for the crack gauge. The manufacturer also warns against some pitfalls of the fasteners, which is why I am avoiding that option if possible.

 

[dik]

Just a 'purist'... masonry repair should properly be done using mortar. I have no idea of how 'glues' deteriorate under UV and a bunch of other 'stuff'. I have no idea of how 'glue' accepts future patching, etc. or aging?

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1674582220/tips/Historic_Brickwork_21-07-05_jucpb9.pdf[/url]

...maybe more information than you wanted.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[phamENG]

dik - I think the glue is for attaching the crack monitor, not repairing the wall...

I hadn't heard of using hot glue. That's an interesting approach. Have you done that with success, XR? I have it come up every now and then but usually shy away because I don't want to drill holes in peoples houses.

 

[rb1957]

is there no underlying cause ? (IDK enough ... had spalling bricks repaired on previous house, yes I know different to mortar cracks ... just asking)

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[phamENG]

rb - there are many potential causes. While you can get a good idea from the shape/location, it's not definitive. Even what most people think of as "settlement" cracks could more accurately called "soil movement" cracks. Soil can shrink or swell with changes in moisture, can heave due to frost, and can settle due to consolidation under load. Any of these can cause cracks that are indistinguishable from one another. If you can measure movement and align it with a particular event (rain after a drought, spring thaw), then you can be reasonably sure of cause.

 

[rb1957]

yeah, my point was you don't want to hide a problem (ie treat the disease, not the symptoms).

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[phamENG]

crack monitors don't hide problems...they're literally measuring tools installed to measure how much the crack moves over time...

 

[dik]

pham... my error. I've generally installed drilled in concrete nails and used vernier calipers...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Craig_H]

Apologies for being out of the office for the afternoon... Pham you are correct that I am looking for an adhesive for the crack monitor rather than a repair itself. Dik, thank you for the comprehensive PDF, I will read tomorrow AM.

I am intrigued by the arts and crafts solution... XR if you have used this method I am all ears.

 

[Ussuri]

We use these, DEMEC Gauges.

The DEMEC pips are small circular discs with a small indent in the centre, which you fix around the crack (normally, 3 off). They are visually less obvious than strain tell tale gauges.

https://www.mastrad.com/demecsg.htm

 

[XR250]

I hadn't heard of using hot glue. That's an interesting approach. Have you done that with success, XR?

I have not tried it or heard of anyone using it. Seems like it should work, though.
Honestly, I have not installed a crack gage in over 20 years.

 

[bones206]

This is a crack monitor that was adhered to a concrete slab with hot glue. It held pretty well considering.

I believe the glue can be removed later with rubbing alcohol and heat.