Hi,
Thanks Lawrence for enlightening me regarding the modern cavity wall slab insulation; I wasn't aware a cavity was still used. Regarding pointing and using a cement rich mortar I would have thought a 3 to 1 mix of sand cement was much too strong? Our bungalow is constructed of sandstone though and this makes quite a difference; I should have stated this earlier. I have an excellent book entitled "The house restorers guide" by the author Hugh Lander and Hugh stresses the dangers of using such a strong cement mix adding that strap or ribbon pointing also damages walls by retaining moisture.
The book actually echoes your suggestions Mark in that Hydrated Lime is the way to go and agrees with you that the lime is best mixed with water in advance making a lime putty and gritty sand can also be added at this stage; a mix which some people have found successful for pointing is cement, lime, clay subsoil (broken down as much as possible) and gritty sand in the proportions 1:1:1:5. Pure lime mortar takes ages to dry out.
I'm sorry if I appear to be answering my own question regarding pointing mortar but I'm interested to learn from others who have gone the lime mortar route. I had to completely replace our random stone chimney stack about 18 months ago because the stones had been pointed with a strong cement mortar mix and this pointing had been struck off proud of the stone face; the stone was virtually destroyed and certainly could not be re-used. When it comes to maintaining our bungalow I want to do everything right and not create problems for the future.
I've spent hours surfing the web for advice and here is a sample of the information on pointing which is available;
http://www.homebuilding.co.uk/advice/exi...tone-walls
Previously I've simply measured out the cement;powdered hydrated lime and sharp sand adding just enough water to give a workable mix; now I need to change this slightly by adding the powdered lime to water to make a putty first and taking your advice Mark I'll not add as much lime but I'll still use the 5 parts of sharp sand to see how it stands up; if it proves too weak a mix it can easily be replaced; the book also recommends raking out to a minimum depth of 22mm; did you take part in writing this book Mark?
If your mortar mix is holding up well Lawrence then all well and good as it works for you; I'm just trying to gather information as I plan to do the pointing next year and all information is gratefully received.
We suffered a thunderstorm a couple of hours ago and the lightning knocked out my computer which has slowed my reply somewhat.
This woodworm thread is turning into a very interesting building thread and I'm very interested in all the replies; thanks everyone for your input.
Kind regards, Col.
Thanks Lawrence for enlightening me regarding the modern cavity wall slab insulation; I wasn't aware a cavity was still used. Regarding pointing and using a cement rich mortar I would have thought a 3 to 1 mix of sand cement was much too strong? Our bungalow is constructed of sandstone though and this makes quite a difference; I should have stated this earlier. I have an excellent book entitled "The house restorers guide" by the author Hugh Lander and Hugh stresses the dangers of using such a strong cement mix adding that strap or ribbon pointing also damages walls by retaining moisture.
The book actually echoes your suggestions Mark in that Hydrated Lime is the way to go and agrees with you that the lime is best mixed with water in advance making a lime putty and gritty sand can also be added at this stage; a mix which some people have found successful for pointing is cement, lime, clay subsoil (broken down as much as possible) and gritty sand in the proportions 1:1:1:5. Pure lime mortar takes ages to dry out.
I'm sorry if I appear to be answering my own question regarding pointing mortar but I'm interested to learn from others who have gone the lime mortar route. I had to completely replace our random stone chimney stack about 18 months ago because the stones had been pointed with a strong cement mortar mix and this pointing had been struck off proud of the stone face; the stone was virtually destroyed and certainly could not be re-used. When it comes to maintaining our bungalow I want to do everything right and not create problems for the future.
I've spent hours surfing the web for advice and here is a sample of the information on pointing which is available;
http://www.homebuilding.co.uk/advice/exi...tone-walls
Previously I've simply measured out the cement;powdered hydrated lime and sharp sand adding just enough water to give a workable mix; now I need to change this slightly by adding the powdered lime to water to make a putty first and taking your advice Mark I'll not add as much lime but I'll still use the 5 parts of sharp sand to see how it stands up; if it proves too weak a mix it can easily be replaced; the book also recommends raking out to a minimum depth of 22mm; did you take part in writing this book Mark?
If your mortar mix is holding up well Lawrence then all well and good as it works for you; I'm just trying to gather information as I plan to do the pointing next year and all information is gratefully received.
We suffered a thunderstorm a couple of hours ago and the lightning knocked out my computer which has slowed my reply somewhat.
This woodworm thread is turning into a very interesting building thread and I'm very interested in all the replies; thanks everyone for your input.
Kind regards, Col.
Happiness is a wreck of a cabinet to restore.
