spongy patch on plastered wall.

[Pell]

I live in a bungalow built in 1936 and have a problem with patches that are spongy to the touch. I have dug out one area of the plaster and find what appears to be cement render which is powdery. Any suggestions please.

 

[malc]

I live in a bungalow built in 1936 and have a problem with patches that are spongy to the touch. I have dug out one area of the plaster and find what appears to be cement render which is powdery. Any suggestions please.

1936 is to early for cement render. they would have used lime mortar. what are you talking about external render or internal base coat ?

 

[johniosaif]

Ah spongycementitus

 

[Pell]

1936 is to early for cement render. they would have used lime mortar. what are you talking about external render or internal base coat ?

Hi! Malc.

It is internal wall render.
I have removed as much of the powdery render as I can, it appears to extend down behind the marble upstand at back of the kitchen worktop. Should I seal it with a weak Unibond solution before repairng the area?

 

[Pell]

Ah spongycementitus

Not very helpful. Funny though

 

[worthwords]

1936 is to early for cement render. they would have used lime mortar. what are you talking about external render or internal base coat ?

this website is concise summary of the construction methods in use by era.

Specification by Period

1930 was transitional - mostly cavity, a lot of gauged lime with gypsum or portland to 'speed up' the set.

Some causes of crumbling

 

[Pell]

Thanks Wordsworth. Interesting data.
I appear to fall in between 2 periods. I have cavity walls up to just below window level and then single brick construction to roof level. I am informed that due to the date 1936 that this was done due to shortages in materials.