Retrofit telescope vents - how???

[Gordo]

3 hours ago, ETC said:

I’d be interested to learn why you don’t agree with this approach. Thanks.

Just my preference based on my concerns about corrosion of reinforcement,  however any technical guidance I have read would agree no void = no ventilation.

[Gordo]

2 hours ago, Hilldes said:

The BBA certificate for the insulated beam and block floor system specified a ventilated void, but I generally thought there was no choice - but that is not really talking from much industry experience. Would be interested learn more about builds with beam and block floors with no void. I've got this vision of a pump truck turning up like a liquid screed truck, but pumps in expanding foam to fill the void ?.

The actual building regulations are really performance requirements. They also provide Approved documents and refer to second tier documents that are presumed to show compliance. However yo do hot have to follow these Approved documents to comply, but it then up to you to demonstrate that you will comply by other means such as a manufacturer 3rd party certification (BBA etc) or another authoritative document such as a BS or even provide a reasoned argument that you are achieving an equal standard. More straightforward just to follow Approved documents.

 

I've never seen T beam floors without a ventilated void so can’t help you much with avoiding vents

 

BTW the guidance is generally that the prepared ground below floor void  should not be below ground levels due to risk of ponding ground water. Might be a good idea to provide a small diameter drainage pipe to bottom of void piped to an external gully for piece of mind

Edited November 3, 2021 by Gordo

[ADLIan]

See BS 5250. If a suspended floor it requires ventilation. At a stretch a ‘suspended’ floor could be designed to have insulation pumped in afterward but it would then effectively become a ‘solid’ floor requiring a dpm (correctly joined to dpc) and positioned to protect the insulation. Probably simpler to build it correctly. I’m sure the bba certificates for these flooring systems will require ventilation without exception.

[Moonshine]

3 hours ago, Mr Punter said:

As you have beam and block you will need the ventilation for Building Regs and probably warranty.  Too late for a ground bearing slab.

 

We did a place that had external periscope vents to the basement.  They didn't look great but served a purpose.

 

 

I knew I saw these before

 

[JOE187]

Just seen this post, could you core drill 125mm holes and put 125mm tube through with adaptor as below?

   https://www.bes.co.uk/domus-supertube-125-elbow-bend-with-spigot-125-mm-od-15545/ then a vertcal lenth of 125mm channel and this adaptor on top

  https://www.bes.co.uk/domus-supertube-125-vertical-90-bend-white-11415/

   Then  use this airbrick!

 https://www.bes.co.uk/domus-horizontal-louvred-airbricks-and-damper-200-mm-x-56-mm-white-15668/

 

Also available in 100mm sizes but not quite regulation airflow.

 

 

[Hilldes]

On 20/02/2022 at 16:45, JOE187 said:

Just seen this post, could you core drill 125mm holes and put 125mm tube through with adaptor as below?

   https://www.bes.co.uk/domus-supertube-125-elbow-bend-with-spigot-125-mm-od-15545/ then a vertcal lenth of 125mm channel and this adaptor on top

  https://www.bes.co.uk/domus-supertube-125-vertical-90-bend-white-11415/

   Then  use this airbrick!

 https://www.bes.co.uk/domus-horizontal-louvred-airbricks-and-damper-200-mm-x-56-mm-white-15668/

 

Also available in 100mm sizes but not quite regulation airflow.

 

 

Thanks @JOE187 will consider that as an option.

 

The other option I'm tentatively considering involves core drilling smaller holes - about 50mm and align them horizontally where the standard telescope vent would penetrate the wall. Then cutting the off the section of telescope vent that would have penetrated the wall and fixing the telescope vent to the wall and sealing it against the core drilled holes. I would add more telescope vents if needed to meet the mm2 of venting required as each vent would pass less air than with the standard rectangular section penetrating the wall.

[DeanAlan]

Just searching re my own issue (post here a few hours ago).

 

Our vents are straight through as no cavity and SIPs above footings.

2 of the vents are too low for our Structural Warranty folks. They need 150mm clear above ground but that is going to be hard.

I was considering external periscope as @Mr Punterimage above and your thinking @Hilldes

 

If I were to connect plastic periscopes to these two compromised vents (it is a no through alley way between my house and neighbours where our extensions from semi-detach houses run parallel and 600mm apart.

 

Question - how would I form a waterproof connection between the airbrick and the periscope? 

- Should I cut the airbrick out and put the periscope end in and mortar that in place or can I form a plastic to airbrick waterproof connection and with what?

 

Then, what should I encase the plastic in for mechanical stability? I could just encase in concrete or (more effort) built a small brick chimney around it.

 

Really interested (desperate for) people thoughts. We're honestly close to loosing our house because we're out of money, out of time and this is the absolute last thing (so they tell me) before the mortgage goes through and we're in the clear. Feels so close but so far at the moment.

[Hilldes]

On 17/01/2023 at 17:37, DeanAlan said:

Our vents are straight through as no cavity and SIPs above footings.

2 of the vents are too low for our Structural Warranty folks. They need 150mm clear above ground but that is going to be hard.

I was considering external periscope as @Mr Punterimage above and your thinking @Hilldes

 

If I were to connect plastic periscopes to these two compromised vents (it is a no through alley way between my house and neighbours where our extensions from semi-detach houses run parallel and 600mm apart.

 

Question - how would I form a waterproof connection between the airbrick and the periscope? 

- Should I cut the airbrick out and put the periscope end in and mortar that in place or can I form a plastic to airbrick waterproof connection and with what?

 

Then, what should I encase the plastic in for mechanical stability? I could just encase in concrete or (more effort) built a small brick chimney around it.

 

Really interested (desperate for) people thoughts. We're honestly close to loosing our house because we're out of money, out of time and this is the absolute last thing (so they tell me) before the mortgage goes through and we're in the clear. Feels so close but so far at the moment.

 

@DeanAlan If I picture your setup correctly, then I guess you have no option but fitting telescopes externally. They may not need sealing to existing air bricks depending on how you conceal the periscopes on the outside - I encased my periscope vents in XPS insulation and rendered across the outer face which essentially seals them in.

 

 

Interested in your original design for these vents not needing to be telescope-periscope. Does that mean all or part of your ground floor build up (suspected floor, insulation and slab) are above DPC level?