What’s Involved with Raising a House Roof?
There are all sorts of ways to add space to a house, most often that’s by adding a room to one or more sides. I’ve designed many additions like those.
I’ve also done a fair number of second-floor additions, which is quite a bit more complicated and expensive. But if you don’t have room on your property to expand out, expanding up might be your only option.
And if conditions are just right, it might be possible to save time and money by lifting off the existing roof and putting it back on top of the new second floor.
Lifting the roof off of a house – and later putting it back on – isn’t something you see very often, but it’s not impossible. And there are other reasons you might think about raising a house roof – when the existing ceiling is too low, for example, or when you want to change a flat ceiling to a vaulted one.
None of those remodeling projects are simple to accomplish, but it can be worth the effort in some situations. Here’s how to figure out if it makes sense for you.
Some Homes Are Better Suited For This Than Others
The first thing you need to find out is what kind of roof structure you have, “stick”, or “truss”. Generally, if you have open space in the middle of your attic, you probably have stick framing. If not, you likely have truss framing.
A stick-framed roof with an attic has room to expand – a dormer for example, might create the additional space you need. A truss-framed roof, on the other hand, doesn’t have any attic space to expand – you’re probably going to have to raise a truss-framed roof to get more space.
And although almost any roof can be raised, the cost of raising a very large or complex roof may outweigh the benefits. From a feasibility standpoint, the best candidates for raising are gable roofs on smaller, simpler homes.
If that sounds like your house, read on.
Raising the Ceiling Height
Let’s say you want a taller ceiling – could you simply hook up a crane, lift the existing roof structure, then make the walls a little taller and lower the roof back down?
You can, and you’ll be the sensation of the neighborhood when you do.
But there’s an important structural issue you need to address first: you can’t simply add a new wall (a kneewall) on top of the existing walls. Doing that creates a “hinge” between the new and existing walls – and that’s a very unstable structure.
Instead, the walls have to be made taller from the bottom up. One way to do that is by installing new, taller wall studs alongside the existing studs. Another method is covering the existing wall and new kneewall with full-height plywood sheathing to eliminate the hinge.
The finer details of how to do this are beyond the scope of this quick introduction to raising a roof, but suffice to say you’re going to need the help of a structural engineer to make it safe.
Adding a Second Floor
As long as we’ve got that crane on site, let’s take the roof up a little more – enough to add an entire second floor between the first floor and the roof we’re removing.
Now we’re less concerned about the “hinge”, because we’re keeping the first floor walls the same height. We’re going to add a new floor structure on top of the walls, then add new second floor walls on that.
Finally, we’ll build new second floor walls and lower that roof back down.
That’s not too complicated but we’ve created additional structural issues to resolve – first is the additional load of the new second floor on the existing first-floor walls – can they handle it?
Second is the additional load on the foundation. Chances are it can take the extra weight, but you’ve got to have this professionally checked out too.
Making a Vaulted Ceiling
In situations like the ones above, it can make sense to lift a roof in one piece and replace it without much structural modification – especially with a trussed roof.
But while a trussed roof can be raised, it can’t be modified to make a vaulted ceiling. You need to start with a stick roof to do that.
Exposing the underside of the sloped rafters is what creates the “vaulted” shape inside that you’re looking for, and that means removing the ceiling joists first.
That breaks the structural “triangle” that holds the roof together, and requires additional framing work to restore structural integrity.
A common solution is adding “collar ties”, which are similar to ceiling joists but a little higher up. A vaulted ceiling with collar ties usually has a large flat area above the sloped sides.
If you want the ceiling vaulted all the way to the top it gets a little more complex, and you’ll need a structural ridge beam.
Other Stuff You Need to Know
Raising a roof, adding a second floor, and creating a vaulted ceiling are all big projects. Big enough that your local building officials are probably going to ask you to bring the rest of the house “up to code”. That can add a lot of cost.
The additional space will also need to be heated and cooled – which may require a larger HVAC system, or even an additional system.
Taller exterior walls almost need more insulation, drywall, and interior and exterior trim and finishes…which reminds me, don’t forget to raise your existing interior walls, too!
Do The Right Thing
Not every home is a good candidate for raising a house roof , but for the ones that are, it can be a cost-effective way to expand living space.
It’s also a sustainable move, since it reuses most of the existing walls and roof and keeps material out of the landfill.
Going “up” doesn’t increase the footprint of your house on the land, and usually makes a more compact, energy-efficient structure.
Save money, landfill space, and energy – all under one roof.