Basement exterior wall can’t hold a plug; what is this material?

[phario]

I’m trying to put some plugs into an interior wall in a late 1800s or early 1900s basement in the south west.

This (see image) is what happened with both a 6mm diameter red rawl plug and also a Fischer duo power fixing. Plugs are about 30mm length. Basically the fixing completely pulled out due to a crumbling wall.

The material is very soft, almost like hard mud.

Can someone explain:

1. What is the brown material I’m drilling into and why can’t it hold anything?

2. How do I get a fixing into this? Do I get a much longer plug, say double the length? Will I eventually encounter hard masonry if I drill deep enough?

 

[JohnD]

Perhaps it is cob. Drill deeper. How thick is the wall?

When you look at the outside, is the wall made of brick, stone or mud?

 

[phario]

Perhaps it is cob. Drill deeper. How thick is the wall?

When you look at the outside, is the wall made of brick, stone or mud?

Hi!

I will drill deeper in the morning.

I’m not sure about the wall thickness because this is a basement wall. I’ve no way of looking “from the outside”!

 

[JohnD]

a late 1800s or early 1900s basement in the south west.

Cob.

 

[JohnD]

I’ve no way of looking “from the outside”!

Look at the same wall where it emerges from the ground.

 

[phario]

Cob.

Thanks. I’m reading up on this.

How would I fix into the wall then? Super deep plugs or that won’t work either?

 

[JohnD]

Join your local Residents of Cob Houses Association.

Generally, you can't.

 

[phario]

Join your local Residents of Cob Houses Association.

Generally, you can't.

I had a look at cob houses and I don’t really think this is one.

The exterior wall that goes down into the basement is really masonry and concrete.

Could it be bad or old aerated concrete?

 

[JohnD]

Nope.

 

[robinbanks]

What are you trying to hang on the wall?

 

[phario]

What are you trying to hang on the wall?

Just some battons so as I can hang other things (say French cleats).

I drilled deeper this morning to about a depth of 10cm. The brown stuff goes through all the way. Very soft.

 

[nicam49]

Dunno if this will help, our house has interior walls of soft cement blocks that have the texture of an Aero chocolate bar. You need to use a special plug, BUT my neighbour has a method he's recently revealed to me, and that is to plug the hole with car body filler or that wood filler you mix with a hardener, and before it sets, push your wallplug into the hole. Once it sets you can screw into it. Genius!

 

[polesapart]

You can set plugs in cob with resin e.g.

Rawlplug R-KF2- Polyester Resin with 2 Nozzles 380ml | Toolstation

2 static nozzle mixers. Polyester, general purpose resin. Economical fixings resin for medium duty load applications. Suitable for multiple use. Partly used product can be reused after fitting new nozzle. Suitable for use in non-cracked concrete, with relatively short curing time.

www.toolstation.com

Goes off once mixed in nozzle so best to drill all fixings at one go.

 

[nicam49]

Perhaps the OP could get advice from his council's planning dept take a sample of the stuff in to show them?.. I've just googled cob houses and it's a possible.

 

[robinbanks]

Planning wouldn't be interested, and I doubt for this application that BC would either..