Routing cable behind dot & dab plasterboard and beneath floor

I’m in a 15 year-old Persimmon house and am trying to route data cables from under the floor to a wall box. I can access under the floor from below and have cut out a hole for the wall box in the plasterboard. The problem is that the route down to under the floor is blocked. I’ve attached a photo taken with a cheap boroscope (plasterboard on left, blockwork on right) and I’m guessing the dot & dab adhesive is run continuously along the bottom of the plasterboard, behind the skirting board. I’m trying to avoid any damage to the first floor room but can’t see how i can get past this barrier. Are there any tricks to achieve this? Is there likely to be any more barriers to this routing? The underlying issue is that I’m not familiar with how this age of house is constructed so I’m kind of working blind.



Thanks in anticipation

If you can reach underneath to check theres no pipes or wires then you'll have to drill down if you've got a long enough bit.

Probably the wall frame work and the floor boards in the way.

pete01 said:

Probably the wall frame work and the floor boards in the way.

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As per https://www.diynot.com/diy/threads/...-i-joists-from-front-to-back-of-house.657160/ the house has I-joists and chipboard flooring. Is the chipboard flooring likely to run up to the block work or would it stop short? I think I’ve chosen a location between joists.

With a slightly better endoscope/boroscope type thingy (you can get them quite cheap if it`s worthwhile) you might be able to better determine exactly what is what).

Those of us who are old enough did not have such things, not even something resembling a dental mirror until quite later on just a small hand mirror or even a left over of 1" mirror tiles mounted on a flexible backing (1" not really big enough to see much and holing a torch in place at the same time. LOL).

Mostly the ubiquitous length of mini-trunking lid to fish about this way and that and poke and pull to get a mental picture of where obstructions were and what they were. Years of practice develops it into a fine art.

Dot and dab could be bad enough at times but it was relatively "the new kid on the block" - lathe and plaster could be good fun but the thousands of dropped "snots of plaster" that piled up at the bottom of the cavity like little pebbles and larger dollops often made it very less than easy even with a reet good fishing technique.
All good fun even coupled with a cheapo metal detector trimmed to different parameters sometimes assisted as did a 10.0 earthwire or an old metal coat hanger could be utilised but you might have to borrow the one you had fashioned into a replacement car ariel for a while.

Dot and dab with plasterboard could be sounded out with the back of a suitable screwdriver handle tapped on the plasterboard for taking sonic readings.
Added to that technique most 3 x 2 battens started at the bottom of the wall right firmly on the top of the floorboards to drill a 20mm to 1" flat bit/spade drill at 90 degrees thru the skirting and perhaps ditto at an angelat the bottom par of the plasterboard - just a dabbing repair with suitable filler in the skirting afterwards and maybe a touch up with a small amount of paint.

One joiner I worked with had a nice habit of packing the bottom backing up away from the floor a bit so after the battens and then boarded both sides before you were even allowed to get to the new partition you then had a chance of easier floorboard removal quite often.

ebee said:

With a slightly better endoscope/boroscope type thingy (you can get them quite cheap if it`s worthwhile) you might be able to better determine exactly what is what).

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The boroscope is a relatively recent purchase, I’ve done plenty of low tech fishing before! What would you recommend as a slightly better one?

Hmm not sure. I got one a few years back it was one of those "when its gone its gone!" things from Aldi and I got it for one specific job at the time, thinking it might be useful another two or three times in my working life, Unfortunately I sort of started windin down to retirement not long afterwards due to accident/illnness but it did not cost a lot but some of their German Engineering is better than some of ours and cheaper.

I might be able to dig it out this morning (dont ask) and give you details for possible comparison.

geojay said:

I’m guessing the dot & dab adhesive is run continuously along the bottom of the plasterboard

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Yes, with the flooring below it as well. They stand on the floor to fit the dot and dab.

Lidl not Aldi - Parkside Inspection Camera PK1 2.8 B2 IAN 385152_2107 . if that helps

ebee said:

Lidl not Aldi - Parkside Inspection Camera PK1 2.8 B2 IAN 385152_2107 . if that helps

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Thanks, I’ll keep an eye on the middle aisle! My £20ish Chinese one from Amazon is not quite good enough. I like the fact I can view the image on my phone via WiFi.

denso13 said:

Yes, with the flooring below it as well. They stand on the floor to fit the dot and dab.

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I took a section of skirting out with a multitool and then a smaller section of plasterboard and the bead of adhesive. That’s given me a route to the floor where I drilled a small hole through. Slightly more damage than I was hoping for but not too bad…

geojay said:

took a section of skirting out with a multitool and then a smaller section of plasterboard and the bead of adhesive. That’s given me a route to the floor where I drilled a small hole through. Slightly more damage than I was hoping for but not too bad…

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Not bad at all, I don't think you had many options.

denso13 said:

Not bad at all, I don't think you had many options.

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Yeah, I’m pretty happy with it. Thank goodness for multitools!

geojay said:

Thanks, I’ll keep an eye on the middle aisle! My £20ish Chinese one from Amazon is not quite good enough. I like the fact I can view the image on my phone via WiFi.

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That’s good image on phone and WiFi o