What is the difference between bearers and joists

When choosing what size timber to use when framing up your deck it is important to note that they all relate to each other and have flow on effects. The distance you space your piles one way determine the size of the bearer and the distance you space your piles the other way determine the size and span of your joists. Following on from our example, the distance between bearers is 1. Our joists are going need to span this distance between the support of our bearers. You can use the table below to determine what distances certain timber can span.

If you are building a low level deck you may require smaller timber 90x45mm spaced closer together. If ground clearance is not an issue then you may opt to use bigger lengths of timber x45mm which will be stronger and can span bigger distances. An exterior deck is prone to water so according to NZ section 7. Using table 7. Design tip — If you are using 32mm thick decking you can save timber and labour by spacing joists mm apart.

The bearers are the main load bearing beams of a deck. As they are responsible for carrying the weight we will need to work out the loaded dimension for each one. Design Note: If you require crawl space under the deck for storage or access it may be better to use smaller timbers that span less distance. Going off of table 6. Span 3 of our deck has joists cantilevered over the last bearer. We need to make sure the joist size we have selected previously can cantilever the distance required.

For this we check out table 7. When building a deck we use the last column of the table for 2kpa floor load. According to table 7. The cantilever on the example deck is mm so we are well under. Design tip — cantilevering your deck can give you more deck area without having to install additional support. However it leaves nothing to fix base boards to if you plan to close off the underside of the deck.

A stringer uses the houses existing foundation to support part of the deck. Stringers can be used instead of having a row of piles and a bearer up against a house. Effectively the stringer is a bearer attached to the house and saves having to dig and concrete additional piles. With your joist spacing determined you can use the mm column to determine what size timber you will need for your joists. The numbers in the mm column refer to the distance that the joists are required to span between bearers.

In our example we have a 2m span between bearers, so we need to scroll down until we find a number over and select the corresponding joist size from the list in the left hand column. You can then determine the number of joists you will need by dividing 10 metres mm by For our exercise we will use 90mm decking boards with a 5mm gap to allow for any movement. As our deck is 6m wide, we will need 6m mm divided by 95mm each board and gap which gives us 64 boards.

Our deck also has to run the length of 10 metres, so we multiply 64 boards by 10 metres to give us lineal metres of decking. You can also at this point calculate the number of nails you will need for your project by dividing the total lineal metres by. In this case we have lineal metres, which divided by. Hopefully, this guide will have given you a good idea of what is required to accurately determine the amount and type of materials that you will need to build your deck.

For further information or any inquiries you might have please get in contact with us via the phone or come into our stores to see us, You can also click on the get a quote link in the menu above to use our web tool and get a price and drawing emailed to you within minutes. To give you an idea of how a deck actually gets built, watch the 1-minute video below and witness how we build one, piece by piece. Thanks for reading. Inspiration About Us Contact. How to Build a Deck — Step One.

Please see an example of mm joist spacing below With your joist spacing determined you can use the mm column to determine what size timber you will need for your joists.

Go to Step 2. Design it yourself. Contact us. As long as everything is levelled. Every granny flat is different. Depending on the engineering requirements you may space your bearers and joists out to different lengths. In most cases you engineer or framing company will let you know the spacing between the joists. In my case they were spaced out at mm Centre. That means from the left leading edge to the next left leading edge for instance they are mm apart.

To get a more comprehensive list of dimensions for your build, I highly recommend checking out the span tables here. I hope reading this article has taught you a lot about how you can build your own granny flat on bearers and joists. Even if you have never built a granny flat before, it is something you can do yourself. Though you may find it physically demanding, it is one of the easier parts for those with little experience.

I built my own Granny Flat from scratch. This blog was created to share everything I learned along the way and to answer common questions. I hope it helps you build your own granny flat as well! LVL beams — A close up. Laying the bearer on a pier.