Hello everyone, I am Renova.

When you decide to try self-renovation, the first thing you need to worry about is dismantle the most.Not only how to peel off the finishing material,House structureIf you do not properly understand this, there is a risk that it will damage safety and earthquake resistance.So this time, we'll be focusing on the key points: "If you keep this close at the very least, you can proceed with the demolition work without hesitation!"Incorporating an engineering perspectiveI'll explain it in a lot.

So, here you go.

1. Understand the structure of a building: First, let's learn about the flow of loads

1-1. What is load?

The house supports the **weight (load)** of the roof, people, furniture, etc.There are two main types:

• **Fixed load (weight of the building itself)**Weight of all the components that make up the building, including roofing materials, exterior walls, interior and equipment.
• **Movable load (variable weights such as people and furniture)**Weight that fluctuates daily, such as people's movements and furniture arrangement.

These loads are transmitted from top to bottom, and ultimatelygroundI'll run away to.Understanding this "load flow" will help you decide whether a wall or pillar is OK to dismantle.

1-2. Basics of shaft frame construction (typical wooden construction method)

Most wooden houses in Japan are "conventional wooden construction methods (siding structure method)."Pillars, beams, girders, and foundationsThe structure is designed to support the house with a shaft frame (skeleton) and reinforce it with braces and plywood.

• Pillar: Supports the load vertically.
• Beams and girders: Connecting the pillars horizontally to receive load.
• Base: The pillars are received at the bottom of the building, joined to the foundation, and the load is transmitted to the ground.

When dismantling, you must cut or remove the pillars, beams, and girders in a random manner.The building's strength is greatly reducedSo you need to be careful.

2. Key points to distinguish structural and non-structural materials

2-1. What are structural materials (main structures)?

• Pillars, beams, girders, etc.To support the homeThick and sturdy square materialis often used.Standard materials such as "105mm square (4 inches)" and "120mm square" are often used in general homes.
  • Pillar: "vertical poles" that support the house vertically.How to tell: It is thick and vertical.It is easily placed at both corners and walls.Most sizes are 105mm square or more.
  • Beams and girders: The "side main character" connects the pillars horizontally and receives loads from above.How to tell: Looking into the attic or attic, you can see a long, thick material running horizontally.They often have large cross sections (such as beams with beams of 210mm or more).
  • Base: It contacts the foundation concrete at the bottom of the building, supports the pillars and transmits load to the ground.How to tell: Square wood that crosses sideways on top of the foundation.Anchor bolts often pass through.
• Straight and stress resistance wallThe part where diagonal material is placed between the pillars and resists horizontal forces such as earthquakes and wind is called "brushing."In recent years, "strength walls" that reinforce the entire wall with structural plywood has also been widely used.
• Hardware (hold-down hardware, hagoita bolts, etc.) Metalware for firmly fastening columns, beams, and bracesAlso be careful when the part is attached.If there is hardware, that's whatStructurally important jointsIt is likely that this is.

2-2. What are non-structural materials (interiors, construction, etc.)?

On the other hand, components that are not structurally important (or auxiliary) areNon-structured materialsis.For example:

• Partition base and interior base: Thin square timber and lightweight steel bases to support wall and ceiling boards.RelativelySlim and low strengthMaterials are often used.
• Curtain boxes, interior boards, etc.: This is a necessary part for interior decoration, but it does not play a role in supporting the entire building.
• Decorative beams (fake beams): Recently, as an accent to the appearance, there are sometimes "decorative beams" that are not actually loaded.

However, cases where it is not possible to judge based on appearance aloneThere is.Carpenters and designers may intentionally hide the reinforcement material, so be sure to check the structure of the base before dismantling.

3. View "role and condition" from the type of wood

3-1. A rough understanding of the properties of wood

There are a variety of timber varieties used in Japanese homes, including cypress, cedar, pine, and imported SPF.However, in the case of self-renovation, the priority is higher to carefully determine whether the material is structurally important or whether it has deteriorated, rather than "which tree species."

• Specific gravity and strengthFor example, cypress is highly strong and has excellent antiseptic and insect repellent properties.SPF (spruce, pine, fur) has its advantages and disadvantages, such as being soft and easy to process, but being slightly less durable.
• Water content: If wood is not dry enough, it will crack in the futureorIt is prone to distorting (warping and bending).Nowadays, artificially dried wood (KD wood) is often used, but older homes have more natural dry wood and higher moisture content.

3-2. Signs of deterioration: cracking, rot, termite damage

If columns or beams become exposed during demolition, check the following points:

1. The size and depth of cracks
   • It is often not a problem if the surface is shallow cracks.
   • Deep cracks or long cracks may cause structural strength to decrease.
   • One criterion is to determine whether the crack exceeds one-third of the cross section of the part.
2. Decay and mold
   • If the wood is darkened or soft to the touch, there is a high possibility of corrosion.
   • Wood moisture contentIt is said that if it is 20% or more, decaying bacteria will likely grow.
3. Termites damage
   • Be careful if the inside of the wood is sparse, or if there are white ants or ant paths (mud tunnels).
   • As termite damage progresses, even if the exterior looks normal, the interior may be in ruins.

4. Even if you think, "Is it a construction problem?", you won't have to doubt it!The idea of ​​an old carpenter

4-1. Meaning of structural slits and "play"

When you disassemble it, you may find areas that think, "There's a gap in this place..." or "The joint seems loose..."However, this may be provided as an engineering necessary play or clearance.

• A gap to absorb the stretching and contraction of wood due to changes in temperature and humidity
• Slits to allow some of the seismic energy to escape
• The rattle is designed to be small with a tenon (with the wood being built into each other).(old technique that does not use hardware)

Although it may appear "distorted" or "not stuck tightly",Old carpenters used rules of thumb to "design that absorbs movement."It may happen.To "fill with stuffing" unnecessarily, it could damage the structure, so make a careful decision.

5. Is this dangerous?Points to be confirmed structurally

5-1. If there is a crack in the pillar

As mentioned above, there are many cases where it is not a problem if it is a superficial crack,If there are large, deep cracks or already bentBe careful.

• If the cross section is large, the strength is insufficientThere is a risk that you will fall into.
• In some cases, the interior may be more corroded than it looks, so try lightly thrusting with a screwdriver or a screwdriver.Is the tree brittle?Let's check.

5-2. Displacement and rust in metal joints

In recent years, homes and renovations,Hold-down hardware, hagoita bolts, square hardwareUse this to securely fasten the columns and beams.If this hardware is loose, rusted or misaligned, it will not be able to provide sufficient strength in the event of an earthquake or typhoon.

• Bolts and screws fall out or loose: It may come off when force is applied.
• Corrosion and rust in hardware: In some cases, it may cause a decrease in strength and require replacement.
• Distinguishing between the design position and actual installation: There is a risk that the structural calculation performance will not be possible.

If you have even a little unsure,Consult with an expert (constructor/designer) to reinstall or reinforceLet's consider this.

6. Before you begin dismantling!Checklist and advance preparation

Whether the demolition will proceed smoothly and safely depends on the research and preparation. First, follow the steps below.

1. Obtaining drawings
   • If possible, get design drawings, structural drawings, and renovation drawings from the time of construction.
   • If there is no drawing, visually and measurements are made in advance to create a rough floor plan and estimate which pillars and walls are the main structure.
2. Building condition investigation
   • It's a relief to have a professional inspect in advance for any signs of termites, corrosion, or water leaks.
   • Consider getting a seismic resistance diagnosis or deterioration diagnosis if necessary.
3. Planning a demolition plan
   • The area of ​​demolition has been clarified, including "posts, beams, and load-bearing walls."The parts that need to be leftUnderstand the following.
   • We estimate the cost and work space based on the disposal costs and the amount of waste materials after disassembly.
4. Preparing safety equipment and tools
   • Wear helmets, dust masks, protective glasses, work gloves, safety shoes, etc.
   • When using power tools (such as impact drivers or circular saws), use them after understanding how to handle them.

7. Actual disassembly work: key points for each process

7-1. Removal of finishing materials

• First, wallpaper and flooring materials,Finishing partI'll peel it off.
• Remove the screws and nails while checking for any screws and nails to expose the base material and structural material.
• Separate and treat the removed waste materialLet's organize it by area to make it easier to do.

7-2. Removal of the base material

• Remove the base plasterboard, plywood, and light ceiling (light steel frame).
• At this stage,Pillars, beams, braces, metalworkYou will be able to see structural components, so please check each one while proceeding.
• Deciding "should it be preserved as a structure?"It is recommended that you put off any items that cannot be done immediately, rather than remove them, and then ask an expert for your opinions later.

7-3. Reconfirming structural materials

• Check again to see if the pillars or partitions are truly removable.**Please use "Is there any problem with earthquake resistance even if you remove it?"** as the key point, and determine whether the load flows and whether there are braces.
• If removal is difficultYou should consider reinforcement methods (additional beams, shifting columns).In this caseDesigners and carpentersIt is safe to consult with.

7-4. When structural repairs and reinforcements are required

• If there are large cracks in the pillars or the hardware is rusted,Repair and reinforcement workLet's do it.
• Attaching metal plates and reinforcement hardware, **beam reinforcement (increase in beam)**, etc.
• If you reinforce the wrong method, it can have the opposite effect.Always check the design with a builder or architect.I recommend this.

8. Don't hesitate to consult with experts!Let's get rid of your worries early

Self-renovation offers a high degree of freedom, allowing you to enjoy building your home as you like, while keeping costs down.Safety and legal aspectsThere is also risk involved.If you have any concerns, don't hesitate to consult a professional.

• Carpenter Carpenters with a good reputation in the local area are looking for old Japanese houses.Traditional structureYou may also be familiar with it.
• Architects and Architects When you ask an expert,Earthquake resistance diagnosisorStructural calculationBased on this, you can get reliable advice.
• Real Estate Company If you are a real estate company that is strong in renovating or renovating, they may refer you to an affiliated construction company or design office.
• Local government housing consultation Local governments may offer free and low-cost construction consultations.Contact your city or town or housing center.

9. Numbers and standards that are useful to keep in mind from an engineering perspective

1. Column cross section dimensions
   • In conventional construction methods, the typical structural column is "105mm square (4 inches) or more."
   • Be careful as dimensions below this may be structurally uncertain.
2. Wood moisture content
   • usually,Under 20%It is considered desirable to maintain the
   • Over 20-30% increases the risk of decaying fungi and termites.
3. Required amount of load-bearing wall (wall amount calculation)
   • In the case of two-story wooden buildings, etc., the building standards law enforcement ordinanceWall amount calculationis defined.
   • Wall magnification (strength of the braces) and wall length must be at least a certain level.Check with the designer for details.
4. Hardware specifications (hold-down hardware, etc.)
   • A "hold-down hardware" is essential for pillars that are subject to pulling force in an earthquake.
   • Older homes sometimes do not have hardware, so additional reinforcements are often made during earthquake-resistant renovations.

10. Summary: Take your time to self-renovate with "safety first"

1. Before demolishing, make sure to grasp the structure of the house (posts, beams, braces, hardware).
2. Before you start to doubt that "is it a construction defect?", you can think about the intentions and engineering reasons of old carpenters.
3. If you suspect cracks in the pillar, misalignment of hardware, rot, or termite damage, consult an expert immediately.
4. Referring to engineering numbers such as wall volume calculations and moisture content, the necessary areas are appropriately reinforced and replaced.
5. Don't overdo it, and proceed with the work with safety equipment and tools in place.

The best part of self-renovation isA sense of accomplishment that renews your home with your own handsIt is located in.howeverRisk of accidentally destroying the skeleton (structure) of the houseIt is also true that there is.By ensuring safety and taking no effort, you can achieve your ideal home while avoiding major problems.

Finally,

How did you like it?

When dismantling, technical terms and engineering numbers may appear, making it a little difficult.However, if you can grasp the key points mentioned here, you can calmly judge even when you are unsure, "Is this the part you can touch or not? Is it a bad part?"

If you have any concerns or questions,Consult with professionals such as carpenters, designers, real estate companies, etc.let's.By obtaining accurate information and advice, you can proceed with renovations safely and securely.

I hope this article will help you self-renovate.Please enjoy the thorough dismantling and renovation with safety first.Thank you for reading to the end.See you next time!