Concrete blocks: medium density or aerated type?
 

I'm currently bricking up two doorways in a 4" party wall between two
terraced houses, as part of a project to reinstate the original
dwellings. I did the first one using medium density blocks, which I
lugged back from Wickes myself, nearly stuffing both my back and the
car suspension in the process... a joiner who later surveyed my
handiwork said I could/should have used the much lighter aerated type
instead. Is that right? If so I could at least use those for the
second doorway!

When we had an extension built a few years ago, with a cavity wall, I
remember the builder used heavy blocks for the outer wall and much
lighter ones for the inner - I assumed I'd need the heavier ones for
the doorway.

I've just noticed in the latest Wickes catalogue (page 36) both types
of block are described as "3.5N" - would that be their load rating?

Thanks
David

Concrete blocks: medium density or aerated type?
 

Lobster wrote:
I'm currently bricking up two doorways in a 4" party wall between two
terraced houses, as part of a project to reinstate the original
dwellings. I did the first one using medium density blocks, which I
lugged back from Wickes myself, nearly stuffing both my back and the
car suspension in the process... a joiner who later surveyed my
handiwork said I could/should have used the much lighter aerated type
instead. Is that right? If so I could at least use those for the
second doorway!

When we had an extension built a few years ago, with a cavity wall, I
remember the builder used heavy blocks for the outer wall and much
lighter ones for the inner - I assumed I'd need the heavier ones for
the doorway.

I've just noticed in the latest Wickes catalogue (page 36) both types
of block are described as "3.5N" - would that be their load rating?


That is their load rating. I would go for 7N high density aerated
blocks. These are slightly more expensive than standard ones, but well
worth it. Any builders merchant will be able to get them for you. FWIW I
used the Thermalite ones, and they were very good.

--
Grunff

Concrete blocks: medium density or aerated type?
 

Lobster wrote:

Thanks. 'High density' and 'aerated' looks like an oxymoron according to
Wickes' terminology but obviously I've misunderstood!

I believe the term high density is used to describe aerated blocks, to
distinguish between the 7N ones and the 3.5N (lower density) ones. Not
to be confused with concrete blocks, which are /really/ high density!

Are these 7N blocks
going to be heavier than both of Wicke' offerings?

They weigh about 30-40% more. They are still very easy to handle, much
easier than concrete blocks. You'll see the difference when you cut one
- the 7N have much smaller bubbles, a much tighter structure.

--
Grunff

Concrete blocks: medium density or aerated type?
 

"Lobster" wrote in message
m...

I'm currently bricking up two doorways in a 4" party wall between two
terraced houses, as part of a project to reinstate the original
dwellings. I did the first one using medium density blocks, which I
lugged back from Wickes myself, nearly stuffing both my back and the
car suspension in the process... a joiner who later surveyed my
handiwork said I could/should have used the much lighter aerated type
instead. Is that right? If so I could at least use those for the
second doorway!

When we had an extension built a few years ago, with a cavity wall, I
remember the builder used heavy blocks for the outer wall and much
lighter ones for the inner - I assumed I'd need the heavier ones for
the doorway.

I've just noticed in the latest Wickes catalogue (page 36) both types
of block are described as "3.5N" - would that be their load rating?

If between two dwellings, use high density concrete blocks for sound
insulation. Houses normally have lightweight high insulated blocks on the
outer walls and the cheapest blocks available on the inner walls. It is
best to have dense concrete blocks on inner walls to give a higher thermals
amass.

Concrete blocks: medium density or aerated type?
 

"Grunff" wrote in message
...
Lobster wrote:
I'm currently bricking up two doorways in a 4" party wall between two
terraced houses, as part of a project to reinstate the original
dwellings. I did the first one using medium density blocks, which I
lugged back from Wickes myself, nearly stuffing both my back and the
car suspension in the process... a joiner who later surveyed my
handiwork said I could/should have used the much lighter aerated type
instead. Is that right? If so I could at least use those for the
second doorway!

When we had an extension built a few years ago, with a cavity wall, I
remember the builder used heavy blocks for the outer wall and much
lighter ones for the inner - I assumed I'd need the heavier ones for
the doorway.

I've just noticed in the latest Wickes catalogue (page 36) both types
of block are described as "3.5N" - would that be their load rating?


That is their load rating. I would go for 7N high density aerated
blocks. These are slightly more expensive than standard ones, but well
worth it. Any builders merchant will be able to get them for you. FWIW I
used the Thermalite ones, and they were very good.

Thanks. 'High density' and 'aerated' looks like an oxymoron according to
Wickes' terminology but obviously I've misunderstood! Are these 7N blocks
going to be heavier than both of Wicke' offerings?
David

Concrete blocks: medium density or aerated type?
 

On Wed, 09 Jun 2004 02:41:10 +0100, Lobster wrote:

..... a joiner who later surveyed my
handiwork said I could/should have used the much lighter aerated type
instead. Is that right? If so I could at least use those for the
second doorway!


Did he say why? Was it due to the load on a concrete slab below?

Concrete blocks: medium density or aerated type?
 

"Derek" wrote in message
...
On Wed, 09 Jun 2004 02:41:10 +0100, Lobster wrote:

..... a joiner who later surveyed my
handiwork said I could/should have used the much lighter aerated type
instead. Is that right? If so I could at least use those for the
second doorway!


Did he say why? Was it due to the load on a concrete slab below?

No, it was more that he thought my blocks were overkill for the job, and
that I'd subjected my spine and car suspension to unecessary grief!

David