Drilling hole into internal cavity

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I live in a detached house with a garage joined to the property with a bedroom above the garage. Separating the garage (and the bedroom above) from the main house is an internal cavity wall of 350mm (including 100mm thermalite blocks either side). I plan on drilling a hole from the top of the internal garage wall into the cavity to pass some data cables through and up into the loft. I’m planning on covering up the holes once the cables are installed into the garage with fire rated foam. Is this the best way and should I be concerned with damp getting up into the loft with the hole made in the garage wall into the cavity?

I’m planning on drilling a 90mm hole into the 100mm thermalite blocks to get into the cavity.
 
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Are you saying your data cable will run the height of the 1st floor, i.e. From garage up to loft?

There's no issue doing that, but if the walls are actual modern thermalite blocks that means a fairly recent construction.....and that could mean a full fill cavity -it might be difficult to get the cable through if its rock walls batts or similar.
 
Are you saying your data cable will run the height of the 1st floor, i.e. From garage up to loft?

There's no issue doing that, but if the walls are actual modern thermalite blocks that means a fairly recent construction.....and that could mean a full fill cavity -it might be difficult to get the cable through if its rock walls batts or similar.

Yeah it’s a new build but about 7 years or so old. When you mean full fill are you talking insulation? If so I have looked straight down the cavity from the loft and was surprised to see no insulation in there apart from up to about 500mm from the ceiling line of the garage itself. I do wonder sometimes if that’s why the room above the garage is pretty chilly in the winter (have tried insulating the garage door!) but ironically the lack of insulation will help me feed the cables down to the garage.

Is there a better way of sealing up the hole than just foam? Is a hole this size anything to be concerned about from a structural point of view - I’m probably overthinking it as there are already two holes in the property for the boiler flue and the extract vent for the kitchen.
 
*Dan*, good evening.

I do not see any dampness being an issue, presuming both holes are internal.

The fire foam will offer protection against fire spread.

Suggest you carefully measure the position of each hole to ensure that they are as close as possible directly above each other.

I would use a long piece of string with a thin weight when beginning to install the cables.

Lower the weighted string from above, and if needed ? use a small mirror and small torch inside the cavity to locate the string and weight, avter fishing the string from the cavity attach the cables and feed and gently pull the cable.

Ken.
 
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*Dan*, good evening.

I do not see any dampness being an issue, presuming both holes are internal.

The fire foam will offer protection against fire spread.

Suggest you carefully measure the position of each hole to ensure that they are as close as possible directly above each other.

I would use a long piece of string with a thin weight when beginning to install the cables.

Lower the weighted string from above, and if needed ? use a small mirror and small torch inside the cavity to locate the string and weight, avter fishing the string from the cavity attach the cables and feed and gently pull the cable.

Ken.


Thanks Ken

There is only really one hole to drill and that’s the one from the garage wall into the cavity itself. When I go up into the loft and look down into the cavity I will be able to see my hand if I put it through the hole as there is nothing at the top of the cavity. I have already got the cables ready at the top and marked out.
 
Cant you drill a clearance hole into the wall at an accute upward angle and push rods up through to pull the cable

that is another option I guess - I could do a smaller hole that way. I was planning on doing just a big enough hole to get my hand in so that I can literally reach in and grab them with someone standing at the top dangling the cables to me.
 
Or???

Drill a smaller hole in the Garage, shine a very bright light into the hole, from the top you can then drop the string, ensuring that the string is stable in the light emanating from the hole, [there will be a pendulum effect] Restrain the line at the top and hook the string and withdraw from the [small] hole in the garage.

I did not realise that you could see into the cavity from above, that will assist greatly.

Ken.
 
Or???

Drill a smaller hole in the Garage, shine a very bright light into the hole, from the top you can then drop the string, ensuring that the string is stable in the light emanating from the hole, [there will be a pendulum effect] Restrain the line at the top and hook the string and withdraw from the [small] hole in the garage.

I did not realise that you could see into the cavity from above, that will assist greatly.

Ken.

yes I was very surprised to see such a big drop lurking underneath 270mm of insulation in the loft!!
 
Same as when they put the brushes in for cavity insulation - 25mm hole at top and bottom, drop chain down and catch through bottom hole with bit of coat hanger.
 
if you pick up a cheap set of rods, you could drill a small hole, feed the rods up and push, find the rod tip in the loft, attach cable and pull back.

https://www.amazon.co.uk/Blue-Spot-...ords=cable+routing+rods&qid=1606821379&sr=8-5

mine are lidl/aldi for less than £10

Personally, I'd also include a bit of strong twine, pull that through at the same time, and leave at least twice the amount in the loft, one end tied to a nail or screw.
That way you can pull other cables through in the future.
it's an extra 10 mins of work for a potential saving of 60-90
 

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