I'm going to build a few layers of lightweight blocks on top of an old oak wall plate as part of roof reconstruction.

My plan is a thin layer of mortar on the oak, then blocks and mortar.

Portland will be ok, not lime wont it?

And I dont need a layer of DPC do I?

Maybe some nails or screws down through the first layer to fix it to the oak, or between the gaps between the blocks?

george

(if i can get the blocks, Travis Perkins said theres a shortage of light weight blocks, the factory's shut down for a month)

On 17/06/16 13:25, DICEGEORGE wrote:
I'm going to build a few layers of lightweight blocks on top of an old oak wall plate as part of roof reconstruction.

My plan is a thin layer of mortar on the oak, then blocks and mortar.

Portland will be ok, not lime wont it?

And I dont need a layer of DPC do I?

Maybe some nails or screws down through the first layer to fix it to the oak, or between the gaps between the blocks?

george

(if i can get the blocks, Travis Perkins said theres a shortage of light weight blocks, the factory's shut down for a month)

I think you have it about right. Lime mortar would be OK. ISTR I've seen
straps used to link blockwork to timber as well as nails driven in. I
would recommend at least for the lower courses to put in some
reinforcement. Either bow tie wall ties or even lay chicken wire in the
mortar: That way the blockwork wont crack as the wood moves - and it will.

You can fill up any subsequent cracks with mastic.



--
"Women actually are capable of being far more than the feminists will
let them."

On Friday, 17 June 2016 13:25:14 UTC+1, DICEGEORGE wrote:
I'm going to build a few layers of lightweight blocks on top of an old oak wall plate as part of roof reconstruction.

My plan is a thin layer of mortar on the oak, then blocks and mortar.

Portland will be ok, not lime wont it?

And I dont need a layer of DPC do I?

Maybe some nails or screws down through the first layer to fix it to the oak, or between the gaps between the blocks?

george

(if i can get the blocks, Travis Perkins said theres a shortage of light weight blocks, the factory's shut down for a month)

If it's an outdoor wall, they usually put lead on top of the wood

On Friday, June 17, 2016 at 1:32:48 PM UTC+1, The Natural Philosopher wrote:
On 17/06/16 13:25, DICEGEORGE wrote:
I'm going to build a few layers of lightweight blocks on top of an old oak wall plate as part of roof reconstruction.

My plan is a thin layer of mortar on the oak, then blocks and mortar.

Portland will be ok, not lime wont it?

And I dont need a layer of DPC do I?

Maybe some nails or screws down through the first layer to fix it to the oak, or between the gaps between the blocks?

george

(if i can get the blocks, Travis Perkins said theres a shortage of light weight blocks, the factory's shut down for a month)

I think you have it about right. Lime mortar would be OK. ISTR I've seen
straps used to link blockwork to timber as well as nails driven in. I
would recommend at least for the lower courses to put in some
reinforcement. Either bow tie wall ties or even lay chicken wire in the
mortar: That way the blockwork wont crack as the wood moves - and it will.

You can fill up any subsequent cracks with mastic.



--
"Women actually are capable of being far more than the feminists will
let them."

yes, the wood might move, so maybe a layer of lime mortar on the wood then use portland cement for the blocks?