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'Weak mortar' used on hundreds of UK new builds

mortar weak

Concerns have been raised about mortar being used on new builds, after a BBC investigation revealed hundreds of UK properties have been built using mortar that does not fall in line with industry requirements.

There are cases where the housebuilder may have simply used the wrong type of mortar but other cases involve errors when mixing and laying the material on site.There have been cases where not enough cement has been used to make mortar leaving to houses “crumbling”.

Phil Waller, a retired construction manager, who has blogged about what he has termed “the weak mortar scandal”, said: “It would appear this issue is both widespread and serious.

“Whatever causes their mortar to crumble, sometimes in under a year, both housebuilders and warranty providers are doing everything they can to limit their costs and keep weak mortar issues quiet, out of the public gaze.”

He added: “Weak mortar cannot be considered as minor snagging, this is the rectification of serious defects often affecting the structural integrity of the home. It cannot be explained away by the industry as a few ‘isolated cases’ either.”

Under National House-Building Council (NHBC) guidelines, mortar in most UK areas should be made of one-part cement to 5.5 parts sand.

However, in severe weather areas more cement in the mix is required to ensure it is stronger and more durable.

In laboratory tests on samples taken from parts of one home featured by the BBC showed the amount of sand was nearly triple the recommended amount.

There are reports of homes with such faults on at least 13 estates in the UK, the BBC has reported.

It is understood that housebuilding company Taylor Wimpey has agreed to replace the mortar in more than 90 separate properties in one estate in the Scottish borders. However, Taylor Wimpey has also said that an assessment by engineers found “no structural issues” with the homes.

There are also construction experts also blame the switch to a new type of factory-mixed mortar, which might pass a different strength test in the laboratory but not always be strong enough in the real world.

A spokesperson for the Home Builders Federation said: “On the extremely rare occasions a poor mix is actually used, structural engineers will assess the building and the house builder is responsible for undertaking the agreed remedial works with the support of the mortar supplier.

“The industry is absolutely committed to delivering high quality homes and the number of homeowners that have serious issues is very low.

“Unlike second hand buyers, new home owners have the protection of a two year builder guarantee and a 10 year structural warranty.”

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Readers' comments (2)

  • Note that The Concrete Society reported on this in CONCRETE magazine in October 2017................

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  • To say that no home were found with structural issues is to say effectively nothing. Until a house has performed in storm winds, who is to say it can perform?

    Commenting on the vertical loading, I found a few bomb blasted buildings in London where you could just lift off the bricks from the mortar bedding and they have lasted since the last war. And these were four and five storey terraces. So for vertical loading, perhaps one can say buildings are performing. Making alterations though might be a bit scary.

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