Lime mortar or Portland ?

[ader]

Hi all,

I'm in the process of buying a house. It's an old hall (built 1901) that's been converted to residential. The walls are solid brick walls with originally lime mortar.

Over time some patches of the walls have been rendered with ordinary grey sand & cement, for example some years ago when the windows were replaced (prior to the conversion).

Would it be sensible or necessary to remove all of this and revert back to all lime mortar? Would it be acceptable to take the top 25mm off and use lime mortar over the top of the portland?

There is a further issue of having some longitudinal steel in the wall that is now pushing out the lime mortar due to erosion.

A structural engineer has visited and suggested all that is needed is to grind out as much of the steel as possible, coat with silicone or similar and then point it over with ordinary sand and cement.

I would have thought it better and more sensible to remove a course of bricks and cut all the steel out and then use lime mortar to repoint. When I suggested this he agreed it would look better aesthetically but would not be any better from a structural point of view.


Any input gratefully received...


A

 

[JohnD]

cement mortar is harder than lime.

It is generally good practice to put soft onto hard, not the other way round.

The cement will crack or spall ifthere is any movement in the lime-mortared wall

What is the steelwork for?

 

[ader]

Thanks for you input

No-one knows the reason the steel is there, speculation is that it was for more strength when originally built as this wall would be the biggest in the building with fewest openings. There is no evidence of steel in any other walls, but there was no evidence of steel in this wall 6 years ago either.

Sounds like lime over portland might be okay (not having to take out the windows and re-do)?