Stapling Insulation: The Expert’s Advice on Technique & Tools

Stapling insulation is the best way to ensure your underfloor insulation withstands the test of time. Other bulk insulation like fibreglass (such as Earthwool, Pink Batts or Gold Batts) are made from loose glass fibres that are glued together which cannot be secured with staples.  Our polyester insulation is strong, featuring its combination of heat-bonded fibres that make it the perfect underfloor insulation.


Stapling secures the insulation forever, holding it firmly against the floorboards so it can do what it does best. Stapling also holds the insulation in place to prevent rodents from nesting under your floor.


We only recommend stapling insulation because we want you to get the best value for your time and money. You don’t want the sad and saggy plastic strapping disaster in this picture to happen to you!


What kind of staplers should I use and how many staples?

When stapling insulation under a floor, there are few things you need to know to ensure your safety and the quality of your job.

It is very much recommended that you only use electric staplers when working under your floor. Electric staplers are double insulated, which means you can’t be electrocuted if you accidentally staple a wire under the floor.

When using a corded stapler ALWAYS use an RCD

When using a staple gun that plugs into a power source, we recommend working with a portable Residual Current Device (RCD) which is an effective add-on safety switch. It cuts the power supply instantly in the instance of an electrical fault of any kind.


Corded Staple Gun

ecoMaster for many years (and for a multitude of reasons) used to use the Ozito 8-14mm Stapler Nail Gun. Each ecoMaster installer would carry 4-5 of these staplers with them for a full day of installing. That being said they were (and still are) a serviceable choice of stapler with one or two quirks. We found they function much better if fed half sticks of staples. They also occasionally pick up residual glue which can cause the firing pin to get stuck. Thankfully the fix for this problem is cathartic! Simply take the offending stapler and smack the head into the nearest solid timber (normally a bearer or stump). This will throw the pin back into the stapler and you should be able to carry on working. 


If that all sounds a little too much like hard work, then we can take a look behind door number 2. 


Battery-Operated Cordless Staple Gun

Some people prefer to use a cordless stapler because they don’t have to deal with the cord while working under the floor. In this instance, we recommend the Milwaukee M12BST Cordless Crown Stapler 10mm 12 Volt staple gun which is available to rent from the ecoMaster store, as well as to purchase from leading tool stores. The Milwaukee staplers are rugged and reliable with only one stapler needed to complete the vast majority of jobs. The staples that work the best are the Arrow T50 10mm staples.


WARNING: Remember to leave your power on, even though your stapler is cordless. We’ll tell you more about why it’s safer to leave the power connected below.

Old-Fashioned Metal Staple Gun

Never use ordinary metal staple guns when stapling insulation under a floor. These are not insulated and there is a very serious risk of electrocution. This is because the metal body of the stapler is highly conductive and nothing will stop that electricity travelling through your body. This will be at best highly unpleasant, at worst lethal. Metal staple guns do definitely have their place as a useful tool but that place is definitely not under a house.

How Many Staples Should I Use?

For best results, choose 10mm galvanised staples.  10mm will be sufficient to penetrate even the hardest of hardwood timbers.

Allow 600 to 900 staples per PACK of insulation.  We have Arrow 10mm T5000 staples available on our webstore. A good rule of thumb when installing is to put a staple into the joist every length of stapler. Depending exactly on the model of stapler this will equate to a staple every 100-200mm which will be adequate. 

So, why not just turn off the power? There’s a really good reason why we always leave the power on.

Why It’s Safer to Leave the Power On

Believe it or not, leaving the power connected while you’re insulating under your floor is the safest thing you can do. Here are two good reasons why:

Having lights fitted under your floor helps you work with ease. The better you can see, the less likely you are to interfere with any wiring, pipes, or ducts you have underneath your home.

Your power supply will tell you straight away if you accidentally staple a wire under the floor. Leaving the power connected means that if you hit a wire, the power will be cut off which is a signal for you to call an electrician to repair it. Doing this will prevent unexpected electrical issues when you finish working, which may result in a serious fire hazard.

And remember, your double-insulated stapler, your portable RCD, and your home’s safety switch will keep you safe from electrocution if you do hit a live wire.


There is an argument for turning the power off before installing underfloor insulation. This does have the benefit of theoretically completely removing the risk of electric shock (unless a previous person has installed a separate feed from the neighbours property!). While this does seem like a good idea, if the power is off and you staple 3 different wires in 3 different parts of the house, it is unlikely in the extreme that it will be readily fixable without destroying your neat installation that you just spent a not insignificant amount of time on.



Of course if you’re under your house and come across the bare end of wires don’t touch them! And if you’re unsure of any aspect of the electrical installation in your home talk to a qualified electrician. 



We wish you all the best as you install your polyester underfloor insulation!