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Restoration & Refurbishment

How do restor crumbly morter

We bought a house which is quite damp. We hacked off all the old wall covering inside to reveal crumbly morter, i believe houses of this age had soft morter to help them "breath" what type of morter should it be replaced with, and how so i know when to stop chipping out the soft stuff ! Brick construction- no cavity- buily circa 1890.

6 Answers from MyBuilder Restoration & Refurb Specialists

Best Answer

Don't hack any more mortar out...

Use lime and sharp sand mortar,I'd be tempted not to go anywhere near a bag of Portland Cement if I where you..brush loose stuff out .
damp or wet /area working on /and repoint/using above.
re damp:- can put in chemical DPC in mortar joint ..only
Trying to get a slate DPC back in can be done but takes a lot of effort.inspect Levels to see if DPC is bridged.look to see a slate line at foot of wall and outside of house
repointing outside may need to be considered.Broken sewer pipes can cause problems if not detected.

Good luck


Answered 16th Apr 2011

The type of morter you should replace the old crumbly morter is a lime and sand mix it would be 3 or 4 shovels of sand and 1 of lime. The depth that you should rake out the old morter is 4 to 6 mm deep hope this helps you.


Answered 7th Apr 2011

A house of this age is bound not to have a dpc course. so i would hack back to expose soft brick, then render walls using a 3/1/1 mix three sharp sand, one lime and one cement. the lime mortar is a more pourous, and will let the moisture from soft bricks to pass through, stopping the chances of damp & mould etc. If still unsure get a tradesman in from my builder to have a look....


Answered 7th Apr 2011

your house was build whit lime morter if you like you can repoint the joints whit lime morter or sand and cement and to try and stop the damp try putting some ronseal over the brickwork after the joints dry its not a big job just sounds like one hope this helps


Answered 7th Apr 2011

Hi, Your house probably was built with slate DPC, this may have brken down. You have several options for the re plastering of the internal walls. There are now water resistant plasters. But you need to halt the damp penetration first. This can be done by injecting a damp proof course. External repointing must be done at a depth of at least 15-20mm any less and it will fall off in a few months, shallow pointing is called flash pointing and its what cowboys do !! check to see if you have solid wall or cavity. Measure the thickness of the walls to find out.


Answered 9th Apr 2011

I agree with Two of the above but "Ronseal" Not recomended to just treat new morter as if there is damp it will migrate.
There are many ways to treat this type of problem,and as stated above the natural product are best for a house of this type and age, if the damp is bad then you may need to think about "tanking" the offending walls with polimar modified products/Natural products this will still allow the wals to maintain the moister but will stop it from entering into the roomn face of the walls.
If you need any other help just ask


Answered 9th Apr 2011

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