How to Safely Modify Your Home Structure for an Open-Plan Layout

Tearing into a load-bearing wall has serious implications, so you must get it assessed and propped first. A licensed builder will accurately and safely open up your space. The alternative – installing steel beams or micro-laminated beams – isn’t a DIY job. It’ll require minor roof alterations and foundation upgrading and you’ll lose space, but if you want the open-plan dream, it’s what you have to do.

Why A Structural Engineer Isn’t Optional

This is the step homeowners most commonly try to skip. Don’t.

A structural engineer runs the numbers, specifying the right beam size and grade to carry the dead and live loads – the dead load being the fixed weight of roofing, framing, and any floors above, and the live load being you and your family and furniture and everything else that enters and leaves a room – without exceeding deflection limits over time. Deflection – gradual sagging under sustained weight – is what causes stuck windows and doors years after a reno as well as cracked ceilings and walls.

They’ll also point out any point loads (guess what that is) where you’ve added a column or post above and it’s not distributing weight back to the beam above in steady-state but pushing it all onto drywall and studs. Fun! Or where you simply stripped off that Thompson Twins wallpaper and realized it wasn’t papering over terrible 80s striated drywall seams after all but rather a support post. Most point loads require a new footing, something a person with a shovel can do for $500 or you can do yourself if you’ve watched someone do it for $500 once.

Choosing Between Engineered Timber and Steel

Your engineer will nominate the beam. All you need to do is familiarize yourself with the alternatives so you can actually have a conversation with someone about the tradeoffs.

Structural steel (commonly I-beams or RSJs) can go a long way over a shallow profile, which is important in rooms with low ceiling heights. The downsides are weight and cost – steel requires a crane lift or multiple men to position and long lead times to get fabricated can blow your program out.

Laminated Veneer Lumber (LVL) is more commonly used on residential reno’s – the engineered timber product has consistent structural properties right along the length of the member and is rated to carry a specific load. It’s a product that can be nailed on site making installation easier, it can be cut to length with no special equipment reducing manufacturing lead time costs which can also speed up your job, and it can be installed by a two-person crew. For the vast majority of domestic situations, it comfortably performs within requirements outlined in Australian Standard AS 1684, Part 3 and it’s much easier to sandwich in with existing timber framing.

For sourcing compliant structurally certified LVL and engineered beams, WA Timber Sales not only supply products that meet residential structural requirements but they can also help your engineer nominate the right product for your application.

Temporary Shoring Before Anything Gets Cut

After you have engineer drawings and your building permit in hand, start by supporting the structure before the existing wall is removed. Acrow props are positioned directly beside the wall, and on each side of the wall, to support it. These adjustable steel vertical supports transfer the load off of the wall so that it can safely be removed. The props take the vertical load that was being carried by the ceiling joist on to the wall framing and transfers it to the floor and then back to the beam in the basement.

Sitting on the floor are steel sole plates. These sole plates are used to spread out the load on the floor so an Acrow prop does not dig directly into the floor. If an Acrow prop digs directly into a floor without a sole plate, the floor can be damaged.

Check The Wall Cavity Before Demolition

This step is too often missed. Walls that have stood for 50 years likely shelter some surprises: plumbing stacks, electrical circuits, HVAC ductwork. Rerouting a plumbing stack that’s running through the wall you want to eliminate can add thousands to the tab once it’s been located, drained, asbestos\-encapsulated/shielded, reflecting in the replastering and retiling of the room where the jackhammer and Sawzall took over.

Before the framing comes down, cavity-plumb it. Remove a section of skirting board or drill a small access hole near the bottom plate to get a good look at the cavity. Use a wire detector to identify electrical wiring after you’ve switched off the circuit. If it’s a bathroom or a kitchen on the other side of the wall, assume there’s plumbing until you’ve confirmed otherwise.

Getting the professional sequence right – engineer, permit, shoring, utilities check, demolition, beam installation – isn’t red tape, it’s what ensures the house you’re planning lasts for another 50 years, not the extraordinary remediation project in a decade.