If you're going to drill holes in your house, you want to know what could be hidden above your ceilings, under your floors and in your walls BEFORE you start. Let me help you with that.
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Introduction
Have you ever thought about what is beneath the surface in your walls, ceilings and floors? It's not something you'd need to worry about normally, it's convenient that your builder tucked everything out of the way and made it all nice and tidy.
That is until you want to put up a shelf, you drill a hole and suddenly you have water pouring down the wall or much much worse.
This is one of four posts:
One on checking what's hidden in your wall before you drill through it (this one)
Let's talk about what might actually be hidden in your walls
In simple terms:
Pipes full of water
Pipes full of gas
Live mains cables
You might think that the pipes are metal so you can't drill through easily, maybe you think cables will have a protective cover over them or something. I'm afraid you're wrong on both counts if you believe either.
Certainly in the UK, water and gas are usually piped in thin copper tubes and if you have a sharp enough drill bit you can drill through them with virtually no effort.
Cables can be protected by metal capping but in many houses they will only be in plastic oval tubing or plastic capping and I've seen older houses with cables literally just buried in the plaster.
In ceilings there will be cables just laying on the plasterboard. There may well be pipes doing exactly the same. Both should be clipped up to the joists so they are not laying there but I can tell you that invariably they're not.
Under floorboards you'll find the same. Pipes and cables directly beneath the boards waiting for you to drill or cut through them. It's way easier to cut notches in the tops of joists to run cables and pipes than it is to do anything else so that is exactly what you'll find.
And as a rule of thumb, the older your house is, the more careful you need to be. If you moved into a new build then a) it should be built to current regulations which are more stringent than they were 30 years ago and b) there's less chance of extra work having been done that you know nothing about.
Where do we begin when we want to find out what's hidden in our walls?
Ok, so do we need to approach every wall, floor and ceiling like we've got no clue what's in it? Unless you already know, YES!!!
First thing to do:
Find out where everything in your house turns off. Do it now.
Mains water - often under the sink in the kitchen. Not only make sure you know where it is but also make sure you can actually turn it off. You'd be surprised how many stop valves (stopcocks, stoptaps) are blocked in by a cupboard, seized up or the head (the turning bit) missing.
Mains gas - usually in a cupboard on the outside of the house, have you got a key? Do you even know where the cupboard is? Just because you don't cook with gas doesn't mean there's no gas in your house.
Other water - if you have a cold water storage tank, find out where to turn off the outlet 9usually by the tank if anywhere). By all means turn off the feed to it but that won’t help you when the 100 gallons of it’s contents are draining down your wall.
If you have a radiator heating system it may have an expansion tank, again, try and find where to isolate the outlet.
Electricity - There should be a "consumer unit" or fusebox somewhere in your house. Older houses are often in the cupboard under the stairs, newer are often on or close to an outside wall at high level and newer still are high enough to be out of children's reach but low enough for you to access easily (which mine isn't). Go find yours and look for the main switch. While you're there, find and press the circuit breaker test button because people never do that and you should do it every 6 months or so. Oh sorry, wait until the person boiling the kettle has finished. And maybe do it in daylight.
Here's my consumer unit, it's high on the wall in my downstairs cloakroom. I've put a red ring around the test button to hopefully help you find yours.
A little bit more info here. The main switch on the right (the big red one) is the one to switch off if you're drilling holes or doing something with the electrics. It's the switch that turns everything off. The others don't.
In my instance the RCD trip for the sockets (that you just tested on yours) is separate. This is not always the case as standards have changed many times over the years. I've written a post concerning standards and legislation, go take a look if you're interested.
Let's start to actually check the walls themselves
I’d suggest you have at least one tool:
I use this cable and pipe detector by Bosch. Reviews on all such things are varied but I get good results with mine.
Let’s look at a wall...
Hmmm. Tells us nothing. That’s actually not a bad thing. It’s got no power sockets, no light switches, no gas appliances, nothing. If it’s an internal wall, see what’s on the other side. If it’s equally blank, check it with your cable and pipe detector. If nothing shows up that’s good.
But before you pick your drill up, go make a tea or coffee while the power and water still works and while you drink it, watch this video from Gosforth Handyman
Good to go now? Great!
As said in the video, use a blunt masonry drill for exploratory holes and take it slowly and gently. If you do hit something it'll do less damage.
Here's some examples from my present home
Just for interest and to echo Andy’s words here’s some more pics of my place
On this wall the radiator pipes run vertically up the centre line of the radiator inside the wall.
On this wall the radiator pipes run vertically up inside the wall about 100mm to the left of the radiator. Yet they go into the wall centrally behind it....
On this wall I’ve never yet figured where they run. It’s a bay window so it’s out of the front of the house and they’re block and beam floors so I’m not convinced they run under it. They probably go left because that’s toward the middle of the house but that’s about as good as I can guess.
Just like Andy mentioned, a mysterious extra bit in a wall is suspicious. This is one of two soil stacks (large diameter waste pipes) that run vertically in my house. Not mains water but you really don’t want to put a hole in it.
Here’s the other one in an odd corner in the living room.
And here in the kitchen, the light switch cable runs vertically upward, the socket cable runs horizontally to the left.
On this one the gas feed to the boiler is hidden in the wall behind it. I only know because I looked to see where it goes out the back of the boiler. Oh and it’s not directly behind the boiler, it runs just at the right side of the left hand switched spur (isolator switch) that you can see.
Once you get to drilling holes, use a blunt masonry bit because they do less instant damage when they hit something and go slowly and gently.
What about checking ceilings?
With ceilings the only thing that is certain is that if there is a light fitting it will quite likely have at least 3 cables running to it. To describe them simply we’ll say one is the ring cable coming in, one is the ring cable going out and one is the switch cable. They will all have power and you want to avoid all of them.
A little side note here, if you ever consider changing your light fittings, apart from TURNING OFF THE POWER FIRST, make sure you understand what each cable does because unless you understand lighting circuits you can pretty much guarantee things will go wrong. Don’t just undo the terminals and pull the fitting off thinking all the wires of each colour join up. They don’t.
So, cables and pipes in your ceiling. The good news is that they will probably just be laying there so with luck you’ll just push them aside. Use an old masonry drill bit to put your hole through and as soon as you're through the ceiling stop the drill and pull it out. Then use an insulated screwdriver to "feel" behind.
And how about checking floors?
Have you got underfloor heating? If yes, don’t drill holes in your floor.
Have you got concrete floors? If yes the chances of cables and pipes are reduced (but not 100% gone) but depending on how deep you are drilling you may damage the damp proof membrane which isn’t ideal. If there's a likelihood of anything at all buried, again a slow approach with a blunt masonry drill is good. Have you got wooden floors? Either wooden floor boards or chipboard? If a conscientious builder has put the floor down he’ll have marked where the pipe runs are. I’ve seen it once in 45 years of playing with houses.
If you have wooden floorboards look for those that have been taken up before. Take them up CAREFULLY and see what’s underneath. Get a torch and look in the floor void. If necessary put your arm down and gauge cable an pipe positions. If there’s no obvious boards that have been up before, proceed as for chipboard.
If you have chipboard floors you have the greatest danger.
Generally we cut an access panel through the boards with a circular saw. Flooring chipboard is usually 18mm or 22mm. If you’re fortunate you’ll see it marked on the sheet or you can find somewhere to measure it, set your saw cut depth to the measurement and no more. If you can’t figure the board thickness, start at 18mm. Find a nail line down a joist and cut as close to the nails as you can without hitting them. Do that on two adjacent joists. Now cut two cross lines to complete the rectangle. Lift the panel out and potentially have an omg moment when you see what you didn’t quite hit. Alternatively you can use a multi-tool with a wood cutting blade but before you start, mark off the cut depth by wrapping some coloured insulating tape or something round the blade. Don’t go past that depth. Multi-tools are good for cuts close to the wall.
You can use a jigsaw but the blade is going to protrude 60mm - 80mm below the board so you’d better hope there’s nothing under there.
If you’re on a tight budget, an old fashioned floorboard saw is an option. You use the curved end section to cut down carefully through the board and then once you’ve cut through you can use the short back section for cuts where you’ve got limited space below and the main cutting length for areas where you can cut with no fear of damaging anything. Again, mark the 18mm or22 mm depth of cut that you want and don't go further than that. Use a marker pen.
Things to do when you've found your hidden pipes and cables
While you have boards up at any opportunity, do yourself and future purchasers a favour and mark cable and pipe runs on your floor so you know where they are before you take boards up next time.
And finally some personal experience
Two stories to close with:
A friend (genuinely wasn’t me) had bare floorboards in his house. Early one morning he walked down the hall in bare feet and felt a shocking pain. On investigation he found a single nail going through the live wire in a cable. The floor had been down around 4 years at that point with never a problem...
When we were working on one of our rooms, one of the bits from my wife’s little Bosch power driver rolled down a small hole in the floor. Just before the carpet was due to be fitted I thought I’d be good and cut a small access hole in said floor to retrieve the bit.
Yup, drilled straight through the centre of a heating pipe. Water tinged with a hint of corrosion inhibitor pouring down the wall of the living room below, staining the recently decorated walls.
There must be a lesson to learn in there somewhere.
So just a reminder: You have found where everything turns off now haven’t you?
Be safe
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