Diamond Drill Bits– This quality carbon steel and diamond tip set is for the big things like copper pipes and steel pipes for gas and water. Large enough to complete the job. Just make sure these bits are not becoming too big for the joist. And be sure to clean out the wood in the bit in between drilling multiple holes. Do not staple too tight as that is bad for the wire- leave a small gap between the wire and the top of the staple

Not less than 3 diameters (centre-tocentre) apart; and located between 0.25 and 0.4 times the span from the support. Those rules may sound complicated, but they are really quite simple. Say you need to drill through a floor joist that is 9 inches tall. The hole would need to be within the middle 5 inches of the joist, because of the 2-inch rule on the top and bottom. That also means, because of the one-third rule, that that the hole cannot be wider than 3 inches.

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Cutting a hole or a notch other than in specified areas can lead to a joist being weakened to such a degree that collapse might occur, even where the loading is below the maximum expected value, especially if made in the middle of a span as shown in Fig 3.

To find out if this might be the case, you can find guidance on notches and holes in solid timber joists for use in domestic properties in section 3.2.2 of Eurocode 5 published by BM TRADA. If you really suspect something is on the other side of that joist and you simply must drill through it, your only option remaining may be to remove the joist. This is definitely the worst-case scenario. The notches should be no further away than 0.25 (¼) times the span. This is to avoid the area of maximum shear force, and the area of maximum bending in the joist The first variable speed range is 0-400 RPM while the second is 0-1320. Chances are that I’ll do most of my work in the low range. The switch has an unusual placement on the bottom of the tool rather than the top. Most of these drills do not automatically come with drill bits, and that is okay. There are plenty of inexpensive options that exist. Just remember: the better the quality, the cleaner the cut and less damage to you floor joists:

Joist Notch and Hole Calculator

Please Note: Every care was taken to ensure the information was correct at the time of publication. Any written guidance provided does not replace the user’s professional judgement. It is the responsibility of the dutyholder or person carrying out the work to ensure compliance with relevant building regulations or applicable technical standards.

These types of joists are engineered and their structural performance relies upon their integrity not being compromised. Like the rules for making notches in joists, the rules for making holes in to your joists are designed to ensure that the structural strength of the joist is affected in the least way possible. If you follow these rules you should not have any concerns about building control and meeting building regulations. Joist Notch and Hole Calculator Single/multiple timber structural beams, rafters, purlins and binders must never be notched or drilled without calculations to justify the remaining timber. Rafters may be birdsmouthed by no more than 1/3rd of the depth. For plumbing clearances, follow the guidelines shown in Figs. C and D. The place where you’ll be most tempted to create oversize holes and notches—under the bathtub is the part of a floor you can least afford to weaken. A cast iron tub, with water and occupant, can weigh in at more than 800 lbs. If you need to cut through a joist, firm up the floor as shown in Fig. E.

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Keep the measurements the same, if possible. You want to keep the heights exactly the same, especially for water pipes. Instead, just feed your wire through the same hole. Even if you need a couple of extra feet of wire, it is worth it. When feed wiring or pipes through existing holes, make sure you avoid combining: Use a different location. If your construction is something a bit smaller than a bathtub, you should easily be able to drill through at a different location entirely, even if you need to use more pipe or wire.

Notches can only be made in the top OR bottom of the joists, (not both) within the permitted area to a maximum of 35mm. Sometimes, however, drilling through a floor joist is about notches, not holes, depending on the type of construction you are doing. In this case, you may be surprised to know that notches need to be smaller than holes. One-sixth of the joist’s height, to be exact. If you’re building an addition or a new home, you can avoid most notching and boring by planning ahead to provide adequate pathways and space for pipes and ducts. Here is the thing though: technically, albeit on a small scale, every time you drill holes in beams and joists you are hurting the structural integrity of your home. Now, that is not to say that drilling three too many holes in one joist will make your house fall down. Another thing to keep in mind is that drilling your hole exactly on the middle line is more of a preference than a requirement. Often you will find that a previous electrician stapled a wire horizontally across the joist along the middle line for convenience.

Finally, if all else fails, drop your pipes and ducts down below the joists and box them in with wood-framed soffits. They’re least obtrusive when run along an outside wall or center beam. Odds are if you are reading this, you already know how to drill a hole. Install the bit in your drill and pull that trigger. However, whenever you are drilling a hole into a floor joist or any other part of your house for that matter, you need to make sure you are being safe and not causing more damage than you need to.