People planning to renovate their homes often want to chop out internal walls to change the size of rooms and the configuration and layout of the house. Unfortunately, some of these walls may be holding up the roof or the floor above, so removing them can cause the roof or upper floor to sag, or worse even collapse. In some cases it’s possible to put in extra permanent supporting structures for the roof or upper floor, but these should be designed by and engineer and installed before demolition work starts.
Even cutting additional doors and windows, or enlarging the existing windows can weaken load bearing walls. Additional beams may have to be installed to transfer the loads over the openings. The remaining portion of the walls must be checked to ensure that they’re able to carry the additional loads from above.
All buildings are supported by some form of foundation. The detail of the foundation will depend on the ground on which the structure is built, as well as the load that the foundation must carry. If the building is on rock the foundations may be light, while buildings on weak ground will have more substantial foundations, even including reinforcing steel. It may appear easy to demolish an internal wall and rebuild it a few centimetres (inches) away, but if the new wall isn’t constructed on a foundation and only on the existing concrete slab there’ll be problems if the concrete slab has insufficient strength to support the new wall. The concrete slab could crack and the wall settle and crack. This is unsightly and can be dangerous.
Sometimes foundations aren’t only there to support the structure but they also must hold the house down. For instance, houses made of lightweight materials in an area prone to hurricanes, tornadoes and cyclones need be firmly anchored to the ground.
Check before adding or removing walls when renovating your home
Get an engineer or an expert builder to check your existing foundations and roof before removing walls, knocking holes in existing walls for additional doors and windows, or before building new walls on top of existing floors. Always take care that you are not weakening the existing structure of your house. This could be dangerous and result in additional costs to repair parts of the house that are damaged when the existing structure is weakened and moves.
See what happened to this house when contractors were working in the basement. The whole house collapsed bringing the neighbours house down as well.
Learn more about renovating and building houses
Paul Netscher has written 2 easy to read books 'An Introduction to Building and Renovating Houses - Volumes 1 and 2'. An Introduction to Building and Renovating Houses Volume 1 deals with Hiring Contractors, Managing Construction and Finishing Your Home. and Designing your ideal home Volume 2 deals with Finding Your Ideal Property and Designing Your Dream Home.
("Great for those that DIY. Very helpful in home renovations!" said a Reader on Amazon.com 5*****)
These books are available from Amazon and other online bookstores in paper and ebook.
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I’m a construction professional, author of several successful construction management books, and a home owner. I’ve made mistakes in construction management, I’ve seen others make mistakes, but importantly I’ve had multiple successful construction projects and I’ve learned from the mistakes. I want to share these lessons and my knowledge with you.
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and 'An Introduction to Building Houses - Volume 2 Finding Your Ideal Property and Designing Your Dream Home'
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