I need to check if the cracks in several walls at home are moving.

I know I can hammer in three nails around the cracks and measure the movement over time with a digital caliper. This is better than the old method of using small gypsum plasters on the cracks.

I remember having seen small transparent devices afixed across the cracks to do that.

Can anybody point me to where I can find such devices or similar ones?

Thanks,


Antonio

"asalcedo" wrote in message
...

I need to check if the cracks in several walls at home are moving.

I know I can hammer in three nails around the cracks and measure the
movement over time with a digital caliper. This is better than the
old
method of using small gypsum plasters on the cracks.

I remember having seen small transparent devices afixed across the
cracks to do that.

Can anybody point me to where I can find such devices or similar
ones?

Thanks,


Antonio




--
asalcedo

They are microscope glass slides:

http://cgi.ebay.co.uk/50-New-Microsc...item4ce5f6d059

Epoxy glue both ends across the crack. If the crack opens or closes
they break.

AWEM

"asalcedo" wrote in message
...

I need to check if the cracks in several walls at home are moving.

I know I can hammer in three nails around the cracks and measure the
movement over time with a digital caliper. This is better than the old
method of using small gypsum plasters on the cracks.

I remember having seen small transparent devices afixed across the
cracks to do that.

Can anybody point me to where I can find such devices or similar ones?

Thanks,


Antonio


The accurate way would be using something like these:
http://www.omega.co.uk/prodinfo/strain_gauges.html

S

On 09/06/10 16:49, asalcedo wrote:
I need to check if the cracks in several walls at home are moving.

I know I can hammer in three nails around the cracks and measure the
movement over time with a digital caliper. This is better than the old
method of using small gypsum plasters on the cracks.

I remember having seen small transparent devices afixed across the
cracks to do that.

Can anybody point me to where I can find such devices or similar ones?

Thanks,


Antonio





Microscope slides (glass) aradlited across would show movement or not
(ie they crack). Not so good for measuring the actual movement though.
But it is the classic way if you want to prove a crack isn't moving...

--
Tim Watts

Hung parliament? Rather have a hanged parliament.

asalcedo wrote:
I need to check if the cracks in several walls at home are moving.

I know I can hammer in three nails around the cracks and measure the
movement over time with a digital caliper. This is better than the old
method of using small gypsum plasters on the cracks.

I remember having seen small transparent devices afixed across the
cracks to do that.

Can anybody point me to where I can find such devices or similar ones?

Thanks,


Antonio


Antonio,

Take two pieces of glass of equal length, scratch a mark in both pieces at
a distance from one end, stick one above the other on the wall on both sides
of the crack on one end of each only (to allow movement of the glass as the
crack widens or closes) with the two marks aligned.

As the wall (and crack) moves, the scratch marks will open or close, showing
the distance of movement (if any) and its direction.

Whatever you use, do not stick both ends of the tell-tale over the crack and
expect it to break if the walls move (the won't, unless you have major
structural movement [and you'll see that without tell-tales]) - always leave
one end free.

Or google for -- glass tell-tales -- for more info.

As a matter of interest, if you have access to a glass cutter and some scrap
(or broken pieces) of ordinary window glass, you can make your own and use
something like an epoxy resin or contact adhesive to stick them to the wall.

Or using the same method, you could even cut the pieces out of the old
ubiquitous empty bake bean tin - and stick these on the wall (or you even
use a couple of small masonry nails to fix them in this case).

Cash