Hello everyone, this is DIY Renova.

The appeal of self-renovation and DIY is the "funny of creating your own home."However, since roofing operations in particular are areas that involve high-speed work and building structure, safety management and correct procedures are extremely important.

In this article, we will thoroughly explain information, specific steps, and points to note from an engineering quantitative perspective, with the theme of "demolition of a slate roof (assuming renovation)" so that even beginners can take action immediately after reading it!

Please take a look until the end.

[1. What is a slate roof?]

Slate roofs are one of the roofing materials widely used in Japanese homes.It is officially referred to by product names such as "makeup slate," "colonial," and "color vest."The main features include the following:

- Relatively lightweight and easy to install
・A wide variety of designs and colors
・Inexpensive and easy to get
・The surface coating tends to peel off due to aging
- Depending on the age of the building, the fibers contained may be asbestos

Particularly, some homes built between the 1960s and 1970s may be made of asbestos-containing slate material.When demolishing a roof yourself, you must first check in advance whether the roof material contains asbestos.

[2. Basic knowledge before dismantling]

Before demolishing a slate roof, keeping in mind the following three points will not only make the work go smoothly, but it will also help to keep safety and avoid legal risks.

[2-1. Weight of slate roofs and the burden on the building]

Before demolishing, first know how heavy the slate roof will have and what the burden on the wooden house is.

A typical slate roof (about 5mm thick) weighs around 20kg per square meter.For example, if the roof area is 100 square meters, it would weigh approximately 2 tons (2,000 kg).Supporting this is wooden structures such as rafters, main buildings, and hut group.Load balance changes temporarily during the demolition process.If you remove the roof material partially, there is a risk that people may be riding on that area intensively or that the scaffolding may become unstable.

If you think about it quantitatively, the following calculation example might be useful:・1 slate (width 910mm x length 1820mm) = approx. 3.3 square meters
・Weight = (3.3 m2 x 20 kg/m2) = Approximately 66 kg
In reality, the thickness varies depending on the manufacturer and the thickness, but each piece of slate is quite heavy.The slate is removed and lowered down repeatedly, so you need to be careful physically.

[2-2. Asbestos Problems and Preliminary Survey]

Older slates may contain asbestos.Asbestos is extremely dangerous when inhaled, with a risk of health damage (such as mesothelioma and lung cancer).Since 2006, the production of asbestos-containing building materials was generally prohibited, but the possibility that they may be contained in houses built before that cannot be ruled out.

If you may have asbestos content, take the following steps:

1. Contact the department responsible for the city, town, or prefecture, or the specialized research institution.
2. If necessary, analyze slate materials using simple test kits or surveys from specialized institutions.
3. If it is determined that it contains asbestos, in principle, avoid dismantling it yourself (legal notification or removal by a professional)

Even if asbestos is not included, disassembly will be carried out in an environment where dust is prone to dust, so equipment such as a dust mask and protective suit are essential.

[2-3. Administrative Procedures and Rules]

When demolishing a roof, you need to be aware of related laws and regulations, such as the Building Standards Act and the Waste Disposal and Cleaning Act.If the scale of the demolition work is large, it may be necessary to register the demolition work, or even if it is being renovated, a prior notification to the local government may be required.

In principle, it is prohibited to handle asbestos-containing building materials by anyone other than a specialist.If the slate in your home contains asbestos, you must either hire a contractor with various licenses or demolish it according to the rules of the local government.Be careful as it is considered "illegal dismantling" as it could be subject to penalties.

[3. Tools and preparations required for dismantling]

The most likely part of beginners is to "which tools should I use and how much budget it costs."Be sure to prepare well before starting work.

[3-1. Tool list]

1. Helmet (protection when flying falls or falls)
2. Safety belt or full harness (prevents falling on the roof)
3. Dustproof masks or gas masks (drain and asbestos protection)
4. Protective or work clothes that can be dirty (minimize skin contact)
5. Gloves and cut-resistant gloves (slate edges may be sharp)
6. Reciprocating saws, saber saws, or electric disc grinders (for cutting metal parts such as ridges)
7. Crowds and hammers (nail removal, removal of the characters)
8. Air nailer or impact driver (helps remove fixing screws)
9. Ropes, carabiners, scaffolding boards and work nets (protective measures against falling objects)
10. Blue tarp, protective sheet (protects dismantled slate and base from rain)

The above is an example of a basic tool.To improve safety, we recommend assemble the scaffolding tightly or leasing temporary scaffolding if possible.There is also a way to use a high-altitude work vehicle, but it can easily exceed the scope of DIY and can be expensive.

Articles about scaffoldingHerePlease check from here.

[3-2. Estimated budget]

The budget for demolition of slate roofs is as follows, including scaffolding, tools, and disposal costs.

・Scaffold installation and insurance premium: Approximately 100,000 to 200,000 yen (for a total floor area of ​​about 30 tsubo)
・Tool purchases and consumables cost: Approximately 50,000 to 100,000 yen
・Cleaning cost: Approximately several thousand yen to 10,000 yen per cubic meter (depending on the region or contractor)

If it contains asbestos, there will be additional costs from a specialist company, which can be even higher (it can range from several hundred thousand yen to over 1 million yen in some cases).For beginners, it is important to prioritize safety and set a solid budget for DIY purposes.

[4. Safety measures]

Roof demolition is a dangerous task that can cause dust to fly.Failure to take safety precautions increases the risk of crashes, injuries and health damage.Before you begin work, be sure to check the following safety measures:

[4-1. Things to note when working at high altitudes]

1. Weather check
   Working on the roof is extremely dangerous in rainy weather or strong winds.Check the weather forecast frequently, taking into consideration that your feet are slippery and that gusts of wind can cause your balance to be unbalanced.
2. Setting work time
   Working after sunset can cause poor visibility and lead to major accidents.Work in a period of bright enough morning to evening.
3. Ensuring scaffolding
   It is extremely dangerous to force yourself to work with just a ladder.If possible, use a scaffold and use a safety belt in conjunction with it.

[4-2. Protective equipment and equipment]

-Helmet: Required to protect the head
・Full harness type safety belt: safer than waist belt type
- Dustproof mask: Even if it contains no asbestos, it is safer to not inhale slate dust.
・Goggles and face shields: Protect your eyes from dust and debris
・Gloves: Recommended for those with anti-slip and prevent hand injuries.

[4-3. Confirming the strength of the structure]

Partial removal of the roof puts a strain on the sheds and rafters, and in some cases the strength of the feet may be temporarily reduced.Especially in the case of old wooden houses, corrosion of field boards and rafters is often progressing, increasing the risk of stepping and collapse.Before you check the condition from the attic with a flashlight or something similar, or check for any damage or holes in the field board.Be sure to check whether you have enough strength to support your weight before starting work.

[5. Overall flow of demolition work]

Finally, we'll begin the practical steps for demolition of slate roofs.For first-time users, the key is to understand the process and proceed with each task carefully.

[5-1. Pre-repair and ensuring safety of the surrounding area]

・Protect surrounding buildings and grounds
Surround it with sheets and nets to prevent any debris and dust from being demolished on the neighboring house or on the road.To prevent neighborhood problems, it's easier to say hello before working.

・Screening of scaffolding
If possible, build scaffolds to surround the entire house and protect it with mesh sheets or similar.It is not only dangerous to work with just a ladder leaning against a slope, but also reduces work efficiency.

[5-2. Removal of building sheet metal and materials]

Before removing the slate itself, first remove any material such as the "munebankin", "keraba" or "elephant drain".These are often secured with screws or nails, so use an impact screwdriver or crowbar to remove them carefully.
At this stage, there are the following points to note:
・When the metal ridge is removed, the highest part of the roof will be exposed, so be careful when allocating time to prevent rain from entering.
・You can also check the condition of the joints and overlapping parts of the slate material at the same time, so you can observe whether there are cracks or mold.

[5-3. Removing the slate body]

Finally, remove the main slate body.It is usually fixed with nails or screws, so follow the steps below.

1. Remove the fixation with a nail remover or air remover
   Remove the nails and screws on the top of the slate.If it is rusty or stuck after many years of age, you may insert a crowbar and pry it off.However, be careful as forcefully applying force can cause the slate to break suddenly.
2. Carefully remove the slate one by one
   It is dangerous to remove multiple copies at once.Remove the securing pieces each piece and slowly pull them apart so that they don't fall down.To prevent a fall, it is best to talk to your partner and work together.
3. Removed slate moves to the ground
   Throwing it directly will cause dust to splash out, leading to neighborhood problems and personal health damage.It's heavy, but as much as possible, use ropes, pulleys, or hand-delivered scaffolding to the ground.
4. Raining after removal
   If you remove the entire roof, the interior of the house may become flooded when it rains.Work in a planned manner, and cover the removed parts with a blue tarpaulin or waterproof tarpaulin.

The slate is more likely to crack than you imagined, and is also heavy.If the roof is inclined large or at a high two-storey building, make sure to use a full harness and safety rope to prevent a fall.

[5-4. Preventing rain from closing and how to protect the work when interrupting work]

Roof demolition can be difficult to complete everything in one day due to weather and work hours.Particularly, for roofs with a large area, such as two-storey homes, work over multiple days is essential.Therefore, when you are interrupting work in the middle, it is important to take measures to prevent the rain from disappearing.

・Protecting in case of partial dismantling
If you haven't peeled all the slate off yet, you can just focus on the parts you removed and close the rain.Specifically, apply a blue tarp or waterproof tarp to prevent the ground floor and rafters from wetting at the removed area.The trick is to cover the edges of the seat firmly up to the eaves and the bottom of the ridge to prevent rainwater from blowing in.Assuming windy days, secure them with ropes, wood, or sturdy protective tape.

・Care after complete dismantling
If you want to interrupt after removing the entire roof, put on a roofing sheet (a waterproof tarp made from modified asphalt roofing).Blue tarpaulin alone is an effective first aid measure, but if left untreated for a long period of time, there is a concern that it will be blown through the gap.It is best to lay down the roof as far as possible and install it so that water flows properly to the gutter (below).

・Use the slope
The roof has a slope, so when applying sheets or roofing to prevent rain from sticking, ensure that there is a route that allows water to be discharged in line with the slope.Be careful as fixing it in the opposite direction to the slope will make it easier to flow backwards.

・How to choose a blue sheet
We recommend using a thick type (highly durable).Inexpensive, thin sheets such as 100 yen stores are not weather resistant for long periods of time and are prone to tearing.It's fine for short-term treatment, but if you plan to suspend a few days to a week or more, choose a sturdy type.

・Fixing method
If the temporary fixation is not good, the seat will flip up the moment the wind blows, and rainwater may invade indoors.Wood is placed on the edges and stacked areas of the roof, and secure it with protective tape or rope to ensure it can withstand strong winds.In some cases, it is safe to temporarily secure the sheet to the field board with staples or tackers, and then hammer wood from above to prevent it from flapping.

・Ready check of the weather forecast
The weather is especially prone to sudden changes during the rainy season and typhoon season, so be sure to keep track of the forecast and schedule your work schedule.Make sure to avoid the roof being extremely open the day before the rain.

As mentioned above, when interrupting, if you pay attention to the three points: "Do not allow rainwater to pass through," "Do not turn the sheet through by the wind," and "Ensuring a water discharge route," it will be easier to protect the inside of the home.When continuing the demolition work, always consult with the weather risks and take appropriate measures to prevent damage.

[6. Check the base after removal of slate]

Once the slate is removed, check the condition of the roofing base, such as the field board and roofing (waterproof tarp).If you are planning to renovate, the base is often repaired here.

[6-1. Check the condition of the field board]

The plain boards that are commonly used as roofing bases in wooden houses are solid wood such as plywood or cedar boards.Check for nail holes or traces of leaks, and for rot or mold.If it appears to be partially corroded, replace the area or add more.

[6-2. Repairing damaged or damaged areas]

・Repair of the Noji board
You can also cut off the corroded part and replace a board of the same size, or stack plywood if the surface is only slightly deteriorated.

・Reinforcement of rafters
If the rafters are weak, attach reinforcements and metal fittings to increase the strength.If you are going to perform the structural calculations of a house simply, consider the load supported by one rafter and the cross-sectional performance of the reinforcement material.For example, if a typical rafter is about 3.0cm x 4.5cm arranged at a 910mm pitch, roughly calculate the weight of the roofing material and personnel carried by each piece and reinforce it so that it does not exceed the design strength.

・Waterproof treatment
Waterproof tarps (roofing) are prone to tearing due to aging.If deterioration is observed during dismantling, it is a good idea to lay out a new roofing.In particular, it is common to use highly durable products such as "modified asphalt roofing."

[6-3. Determine the direction of renovation]

After dismantling the slate, you will decide what kind of roofing material you will use in the future and how to renovate it.For example, the following options are possible:

1. Replace with new slate material
2. Uses metal roofs such as galvanized steel sheets
3. Incorporate insulation to improve insulation
4. Changed roofing materials such as tiles to emphasize design.

Each has its pros and cons, but please make a comprehensive judgment, including cost-effectiveness and ease of maintenance.

[7. Disposal of waste materials and recycling]

Waste material produced during the dismantling of slate is considered industrial waste.It must be disposed of properly using the following methods:

[7-1. How to dispose of slate]

・Check local government rules
In some areas, you can divide them into small pieces and get them out of household waste, but in many cases you will need to ask a professional collection and transport company for construction waste.

・Confirm the manifest
If you are treating it as industrial waste, you will need to have it issued a "Industrial Waste Management Card (Manifesto)" when you ask a contractor.This is an important document that indicates that the process is being processed legally.

[7-2. Requests from industrial waste disposal companies]

As the slate is dismantled, it is common to ask a specialist to collect it rather than bringing it directly to a municipal processing facility by yourself.Get quotes from several companies and compare costs and responses.If there is a possibility that asbestos content, a more specialized industrial waste company will be required.

[8. Tips for improving work time, cost, and efficiency]

Here we will explain the rough guideline for the work time and cost of demolition work, as well as key points to help you proceed efficiently.

[8-1. Example of work schedule]

As an example, we will assume that the roof of a two-storey wooden house (total floor area of ​​approximately 30 tsubo) is completely demolished.

Day 1
"Scaffold assembly" + "Preparation"
We asked a contractor to assemble the scaffold and installed a protective sheet.

Days 2-3
"Removing the ridge sheet metal and the materials" → "Removing the slate material"
The work is done with 2-3 people, and the team proceeds in an attempt to clear weather.The roofing material was removed in 3 days.

Day 4
"Checking and repairing the base" + "Sorting and disposing of waste materials"
Repairing of the field boards and rafters is carried out simultaneously.The removed slate scrap material was handed over by truck to a collection company.

Day 5
"Roofing replacement and temporary installation"
Prevent leaks while preparing for the next construction work.

This is just a reference example, but it is easily affected by weather and personnel reasons, so it is safe to reserve a 1-2 week span with ease.

[8-2. Cost reduction concept]

1. Make it clear what you can do on your own
   In a completely DIY process, such as assembling scaffolds and arranging high-altitude work vehicles, it is safer to entrust the work to a contractor that is dangerous or requires technical skill.On the other hand, simple tasks such as removing slate and separating waste materials can be reduced by performing them on their own.
2. Use rental tools
   Power tools and safety equipment can be expensive when you purchase them.If you are using it infrequently, use tool rental services from rental shops or home improvement stores.
3. Bulk purchases or joint purchases
   If you are renovating at the same time as your neighbor, you may receive a discount on material costs or a lump-sum discount on industrial waste collection.

[9. Summary and next steps]

Slate roof demolition operations are classified as "high difficulty" and "high risk" among the general DIY projects.However, if you acquire the correct knowledge and preparation, and proceed with the work while complying with the laws and safety aspects, you will be able to fully undertake the work within the scope of self-renovation.If you keep the following points in mind, even beginners will find it difficult to dismantle the structure.

1. Be sure to check whether it contains asbestos
2. Demand to the government and follow legal rules
3. Take thorough measures to ensure safety during high-altitude work (scaffolding, full harness, dust prevention measures)
4. Carefully check the basement boards and rafters, and repair them if there is corrosion.
5. Dispose of waste materials in an appropriate manner to avoid any inconvenience or illegal activities to those around you.
6. Have plenty of time to manage schedules and do not overdo it

Towards the big goal of renovating, it is important to first ensure that the demolition work is successful safely.The roof is an important part of protecting your home from wind and rain, so please do not skimp on any underlayment repairs or new roofing materials before dismantling.We hope you will experience the joy of incorporating professional knowledge as needed and updating your home to a better condition with your own hands.

We would be happy if this article could help those who are taking on the challenge of demolition of slate roofs.The best part of DIY is the sense of balance, "Do what you can do yourself, and if you find the difficult part, you need to ask the professionals to cooperate."Try to achieve a satisfying self-renovation experience in the three ways of safety, quality and cost.

The above explains the amount of slate roof demolition (assuming renovation) over 6,000 characters.We cover detailed engineered quantitative data and safety measures so that even beginners can easily imagine specific processes.When you start working on actual work, please make use of the checklist in this article and work with safety first.

In the first place, how much can I do to renovate my home?Where should I start?In other words,Herefrom.If you would like to know more about the specific renovation process and construction,HerePlease also take a look at the page!

Reference video:

This video is useful for external users!

1: Renovation Channel

2: Home Life Paint Reform Channel