Do you have a way to bring the loft board up?
You might be raring to go to board your loft. But are you having to use separate ladders and hoisting yourself in? Check out my post on How to install loft ladders on the first part of this job. Firstly I needed an easily accessible route to carry tools and parts into the attic. Secondly this would allow me to bring larger storage items into the enlarged hatch. Thirdly with a dedicated hatch and loft ladders, going up and down for access was as easy as going into another room.
If you want to do it by the book
Let’s talk insulation. If you plan on selling your house or keeping it energy efficient as possible then keep reading. In the UK the recommended thickness of fiberglass wool insulation is 270 mm. The table below shows how this has changed over the years and how the thickness requirement as tailed off.
So for the majority of the 20th century, to board a loft was a significantly easier job then it is today. This was because with the insulation height being under the joist height, you could just screw boards straight into the joists.
How high are your joists?
I’d be pretty certain they’re not 270 mm high. That would mean the height would be over 10 inches! So the first recommended step is bringing your insulation up to 270 mm before the loft board goes on. It’s unlikely the recommended about will increase again because you get diminishing returns from this point.
You can build this up in layers with products such as this. You would do two layers of this 100 mm insulation then top it up with a 50 mm variant to bring the total to 250 mm.
You have a decision to make on how you board your loft
This height of 270 mm brings an added complexity of how do you board your loft to the joists? Do you
- Board anyway and squash the insulation down?
- Reduce the amount of insulation for where you want to board
- Board the loft over the insulation
- The easiest but most expensive way
Whatever you do, don’t do option 1. Fiberglass insulation only works effectively with air pockets as that limits the heat transfer. By squashing it down it drastically reduces it’s effectiveness. You can also bring in additional problems such as condensation on the underside of the boards.
Providing you’re using a small amount of storage space you could go for option 2. The loft board itself provides insulating properties as does the items you store on top of it. So whilst it’s not the best method it would do for a small area.
3. Loft board over the insulation
The best way is to go with option 3. Bring the level of insulation up to 250 – 270 mm and to board over the insulation. There are two popular ways in doing this.
The Easy way
The quickest and easiest way to board the loft are basically to have them on stilts. The go to brand is Loft Legs. If you only intend on storing Christmas decorations and empty suitcases then this can be the solution for you. There are plenty of videos on how to install them so I don’t need to cover it here.
And the hard way
I wanted to future proof my storage solution as I can’t predict what I might want to store in the future! The fact is I never felt comfortable using loft legs as it is basically relying on your loft boards to sit on stilts.
The way to maintain the height and have the loft boards raised in place is by building a timber subfloor. This would be cross battened on top of the original joists at a 90 degree angle.
This subfloor would rest on each point it crosses at the joist it sits on. It’s a timber frame where each new joist sits at a 90 degree angle to the original joist below it. This would ensure that any weight on top of the loft board would then be distributed across the timber subfloor which in turn would distribute to several joists. In basic physics this is a lot sturdier than loft legs which focuses the pressure to single points on the joists. I’d feel more comfortable knowing that the weight stored eventually gets distributed down to a supporting wall.
Some maths
If you intend on storing significant amounts of weight then it would be worthwhile doing some calculations. I believe for most of us DIYers this wouldn’t be necessary in traditional builds. If you Google joist weight spans you’ll see the engineered calculations for how much weight you can store per square metre. It takes into account-
- Height and width of timber joists
- Spacing of joists
- Span the joists cover
- Type of wood used
As you can see you can get pretty granular with the variables but the first three will give you a good indication of what you are working with. For example if you have 3 x 2 inch timber joists that span over 6 metres with 600 mm spacing then you have you may need to rethink the whole storing idea! The following is a pictorial walkthrough of how I went about my loft board setup.
And last thing to note before your first loft board
It’s worth having a think about how much storage space do you need? The wife thought I would be boarding the full loft including the roof to stop mortar coming down. I had to reason with her that the cost of wood isn’t cheap and that we can start off with a quarter of the space. We could then see how quick does that fill up and then add more storage when we need it. This meant the upfront cost is reduced and prevents us getting into a bad habit of hoarding because we have the space to.