Overflow pipe drilled through DPC

[Mr Creosote]

The initial message was deleted from this topic on 27 July 2026 at 09:10

[CambsBill]

Unless the hole is lower on the inside than on the outside then he hasn't drilled through the dpc, just straight through the brick.

[InitialDave]

I agree, it looks like it's just above the DPC based on your description.

[smokey mow]

You should have a cavity tray installed above the air brick so yes it will have been drilled through to fit the pipe.

The purpose of the cavity tray is to deflect any moisture and condensation in the cavity to the outside and prevent it from pooling on the top of the air brick where it could then soak to the inside blockwork.

What they’ve done is wrong but if you’ve not noticed any issues then it’s likely not going to be a problem.

[sherman]

I would be filling the gap in the hole with some brown silicone. Thats an ideal access point for a mouse.

[Mr Creosote]

smokey mow said:

You should have a cavity tray installed above the air brick so yes it will have been drilled through to fit the pipe.

The purpose of the cavity tray is to deflect any moisture and condensation in the cavity to the outside and prevent it from pooling on the top of the air brick where it could then soak to the inside blockwork.

What they ve done is wrong but if you ve not noticed any issues then it s likely not going to be a problem.

Thanks. If I do get issues, what would the solution be? Presumably we’d have to remove bricks to patch the DPC? Is this a big job?

[smokey mow]

Mr Creosote said:

Thanks. If I do get issues, what would the solution be? Presumably we d have to remove bricks to patch the DPC? Is this a big job?

Pretty much as you describe. Take 3 or 4 bricks out above the air brick which should then give enough room to lap in a new tray. Replace bricks and then make good.

Roughly half a days work for a competent builder.

[Mr Creosote]

Thanks!