As a Software Engineer at Johns Manville, you play a pivotal role in driving technological advancement and innovation within the company. Your responsibilities span the design, development, and implementation of software solutions that enhance operational efficiency and product quality. In a company renowned for its commitment to safety and sustainability, your contributions directly impact the performance of products used across various industries, from residential to commercial applications. This role is critical not only for the functionality of internal systems but also for the development of customer-facing applications that improve user experience and satisfaction. You will engage with cross-functional teams, tackling complex challenges and leveraging your technical expertise to create robust software solutions that support Johns Manville’s strategic initiatives. The work is dynamic and demands a proactive approach, offering opportunities to influence product direction and contribute to a culture of innovation.
Phone Screening
reportedInitial call with a recruiter or HR representative to assess candidate qualifications.
What to demonstrate
- Initial call with a recruiter or HR representative to assess candidate qualifications
- Depth in Process Engineering (Industrial Processes)
How to prepare
- Be able to walk your CV end to end in two minutes, and say why this company specifically.
- Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.
Technical Interviews
reportedOne or more rounds of interviews that may include coding challenges or case studies.
What to demonstrate
- One or more rounds of interviews that may include coding challenges or case studies
- Depth in Process Engineering (Industrial Processes)
How to prepare
- Answer aloud and timed: What methodologies do you follow in your software development process?
- Answer aloud and timed: How do you ensure the quality and maintainability of your code?
Team Meeting
reportedOpportunity to meet with future colleagues to evaluate team dynamics and cultural fit.
What to demonstrate
- Opportunity to meet with future colleagues to evaluate team dynamics and cultural fit
- Depth in Process Engineering (Industrial Processes)
How to prepare
- Answer aloud and timed: Discuss a project where you had to collaborate with diverse teams.
- Answer aloud and timed: Describe how you would approach debugging a complex software issue.
PracHub editorial advice for the preparation topics above.
Understand the company culture
Familiarize yourself with Johns Manville's values and mission. This knowledge will help you frame your answers and demonstrate alignment during interviews.
Prepare specific examples
Be ready to discuss your past projects in detail, including challenges faced and solutions implemented. This illustrates your problem-solving process effectively.
Practice coding
If coding is part of your interview, practice common algorithm problems and be ready to discuss your thought process clearly.
Ask questions
Show your interest by preparing thoughtful questions about the role, team dynamics, and company culture. This will also help you gauge if the company is the right fit for you.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Write a function to solve [specific algorithm problem].
Write a function to solve [specific algorithm problem].
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
Explain the time and space complexity of your solution.
Explain the time and space complexity of your solution.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
Discuss the trade-offs between different data structures for this problem.
Discuss the trade-offs between different data structures for this problem.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
Replace offset paging on the resource feed with keyset
resource holds resource_id, tenant_id, owner_user_id, title, body_ref, version, status ('draft','active','archived','deleted'), created_at, updated_at, deleted_at, with an index on (tenant_id, status, updated_at DESC, resource_id DESC). The listing endpoint returns active resources for one tenant, newest update first, 50 per page, today with LIMIT 50 OFFSET n. Tenants reach page 400 and rows are created while they read. Write the keyset query, define what the cursor carries and how it is encoded, and say which part of the index each predicate uses. Assume PostgreSQL 16.
Approach
- Name the two failures separately. OFFSET 20000 makes the server produce and discard 20,000 rows, so page cost grows with depth rather than with page size. Independently, any write that changes how many rows sort above the offset moves the window between two fetches, and the direction decides which anomaly you get: an insert lands at the head of updated_at DESC and pushes already-returned rows down past the boundary, so they are returned a second time; a delete above the offset, or a row whose updated_at is bumped above the cursor, pulls rows up and one is never returned at all. Nothing in the response reveals either.
- Write the seek: WHERE tenant_id = $1 AND status = 'active' AND (updated_at, resource_id) < ($2, $3) ORDER BY updated_at DESC, resource_id DESC LIMIT 50. The row-value comparison is one index range rather than a disjunction, and both columns are NOT NULL, which is what makes that comparison well defined.
- Map each predicate onto the index: tenant_id and status are equality on the leading columns, (updated_at, resource_id) is the range, and the ORDER BY matches the index order so no Sort node appears and the scan stops after 50 rows. The DESC in the definition only matters for mixed directions — a plain ascending btree on the same columns is read backwards for this query.
- Put both sort columns in the cursor and nothing the client can tamper with into another tenant: base64 of (updated_at, resource_id), validated server-side, with tenant_id taken from the principal.
Follow-up
- The client asks for 'jump to page 400'. What do you offer instead, and what does the honest version cost?
- Sort order becomes user-selectable across four columns. How many indexes is that, and which would you refuse to add?
Find version gaps and relay lag with window functions
outbox_event holds event_id, aggregate_type, aggregate_id, aggregate_version, event_type, payload, status ('pending','published','dead'), attempts, created_at, published_at. A projection is missing rows and you must decide whether the relay skipped events or the consumer dropped them. Write three queries over the last seven days: one listing every aggregate_id whose published aggregate_version sequence has a hole, one giving per-day counts with a running total, and one returning the newest published event per aggregate. For each, say where the window function is evaluated relative to WHERE and LIMIT. PostgreSQL 16.
Approach
- Gaps: compute lead(aggregate_version) OVER (PARTITION BY aggregate_id ORDER BY aggregate_version) in a subquery, then filter next_version <> aggregate_version + 1 in the outer query. Window functions are evaluated after WHERE, GROUP BY and HAVING and before the outer ORDER BY and LIMIT, so the predicate cannot sit in the same WHERE clause and PostgreSQL 16 has no QUALIFY.
- Say what the seven-day filter does to the answer: it truncates every partition, so the first row per aggregate has no predecessor inside the window and a hole spanning the boundary is invisible. Widen the window, or join to resource.version as the authority for the true maximum.
- Running total: SELECT date_trunc('day', created_at) AS d, count() AS n, sum(count()) OVER (ORDER BY date_trunc('day', created_at) ROWS UNBOUNDED PRECEDING). An aggregate inside a window call is legal because grouping runs before windowing. The grouping key is unique per row here so ROWS and RANGE agree, but write the frame anyway — over ungrouped rows with tied timestamps the default RANGE frame pulls in every peer row and the total jumps.
- Newest per aggregate: DISTINCT ON (aggregate_id) ... ORDER BY aggregate_id, aggregate_version DESC is the cheap PostgreSQL-only form when an index matches that order; row_number() OVER (PARTITION BY aggregate_id ORDER BY aggregate_version DESC) = 1 is the portable form and needs a subquery for the same evaluation-order reason as the gap query.
Follow-up
- Relay failover redelivers events. Does a duplicate break the gap query, and how would you detect one from this table alone?
- Turn the gap check into a continuous monitor rather than a query someone runs after an incident. What does it watch?
Describe a challenging technical problem you faced and how you solved it.
Describe a challenging technical problem you faced and how you solved it.
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
What methodologies do you follow in your software development process?
What methodologies do you follow in your software development process?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
How do you ensure the quality and maintainability of your code?
How do you ensure the quality and maintainability of your code?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
Discuss a project where you had to collaborate with diverse teams.
Discuss a project where you had to collaborate with diverse teams.
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
If given a specific scenario where performance is lagging, how would you diagnose the problem?
If given a specific scenario where performance is lagging, how would you diagnose the problem?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
Describe how you would approach debugging a complex software issue.
Describe how you would approach debugging a complex software issue.
Approach
- Establish what changed and when, before forming any theory.
- Pick a bisection that eliminates candidates whichever way it turns out.
- Check the instrumentation before believing the symptom.
- Separate the trigger from the cause; the deploy is rarely the bug.
Follow-up
- What would you look at first, and what would it rule out?
- How would you tell a cause from a coincidence here?
Built from the rounds and topics Johns Manville candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Johns Manville loop
- Write out the reported sequence: Phone Screening, Technical Interviews, Team Meeting.
- For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.
Deliverable: A one-page map of the 3 reported rounds, with the weakest marked.
02Work Process Engineering (Industrial Processes)
- Spend the session on Process Engineering (Industrial Processes), which Johns Manville candidates report being tested on.
- Write one worked example in Process Engineering (Industrial Processes) and time yourself on it.
Deliverable: One timed worked example in Process Engineering (Industrial Processes).
03Work Recruiting / Talent Acquisition Interview Process
- Spend the session on Recruiting / Talent Acquisition Interview Process, which Johns Manville candidates report being tested on.
- Write one worked example in Recruiting / Talent Acquisition Interview Process and time yourself on it.
Deliverable: One timed worked example in Recruiting / Talent Acquisition Interview Process.
04Work Production / Process Engineering Domain
- Spend the session on Production / Process Engineering Domain, which Johns Manville candidates report being tested on.
- Write one worked example in Production / Process Engineering Domain and time yourself on it.
Deliverable: One timed worked example in Production / Process Engineering Domain.
05Answer out loud: Technical / Domain Questions
- Answer aloud, timed: Can you explain your experience with [specific programming language or technology]?
- Answer aloud, timed: Describe a challenging technical problem you faced and how you solved it.
Deliverable: Spoken answers to 2 reported Technical / Domain Questions question(s), under time.
06Answer out loud: Problem-Solving / Case Studies
- Answer aloud, timed: Describe how you would approach debugging a complex software issue.
- Answer aloud, timed: If given a specific scenario where performance is lagging, how would you diagnose the problem?
Deliverable: Spoken answers to 2 reported Problem-Solving / Case Studies question(s), under time.
07Answer out loud: Behavioral / Leadership
- Answer aloud, timed: Tell me about a time when you had a disagreement with a teammate. How did you handle it?
- Answer aloud, timed: Describe an instance where you took initiative in a project.
Deliverable: Spoken answers to 2 reported Behavioral / Leadership question(s), under time.
Expand any day for tasks and deliverables. Your progress is saved on this device.
Behavioural rounds judge the decision you made and what it cost.
Can you explain your experience with [specific programming language or technology]?
Can you explain your experience with [specific programming language or technology]?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- Name the disagreement and how you resolved it with evidence.
Follow-up
- What would you do differently if you ran that again?
- How did you know your change caused the improvement?
Provide an example of a time when you had to make a trade-off between performance and maintainability.
Provide an example of a time when you had to make a trade-off between performance and maintainability.
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- Name the disagreement and how you resolved it with evidence.
Follow-up
- What would you do differently if you ran that again?
- How did you know your change caused the improvement?
Tell me about a time when you had a disagreement with a teammate. How did you handle it?
Tell me about a time when you had a disagreement with a teammate. How did you handle it?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- Name the disagreement and how you resolved it with evidence.
Follow-up
- What would you do differently if you ran that again?
- How did you know your change caused the improvement?
Describe an instance where you took initiative in a project.
Describe an instance where you took initiative in a project.
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- Name the disagreement and how you resolved it with evidence.
Follow-up
- What would you do differently if you ran that again?
- How did you know your change caused the improvement?
What motivates you in your work, and how do you stay engaged?
What motivates you in your work, and how do you stay engaged?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- Name the disagreement and how you resolved it with evidence.
Follow-up
- What would you do differently if you ran that again?
- How did you know your change caused the improvement?
- 01
Can you explain your experience with [specific programming language or technology]?
- 02
Provide an example of a time when you had to make a trade-off between performance and maintainability.
- 03
Tell me about a time when you had a disagreement with a teammate. How did you handle it?
- 04
Describe an instance where you took initiative in a project.
How difficult is the interview process, and how much preparation time is typical?
The interview process is considered average in difficulty, with candidates typically preparing for a few weeks. Focus on understanding the technical skills required and practicing behavioral questions.
Johns Manville Software Engineer candidate reports ↗What differentiates successful candidates?
Successful candidates demonstrate a blend of strong technical knowledge, effective problem-solving skills, and a cultural fit with the values of Johns Manville. They can articulate their experiences clearly and show adaptability.
Johns Manville Software Engineer candidate reports ↗Can you describe the culture and working style at Johns Manville?
The culture at Johns Manville emphasizes teamwork, safety, and innovation. Collaboration is key, and the company fosters an inclusive environment where all employees are encouraged to contribute their ideas.
Johns Manville Software Engineer candidate reports ↗What is the typical timeline from the initial screen to the offer?
Candidates can expect a timeline of 2-4 weeks from the initial screening to receiving an offer, depending on the interview stages and schedules of the interviewers.
Johns Manville Software Engineer candidate reports ↗Are there remote work or hybrid expectations for this role?
While specifics may vary, many roles at Johns Manville offer flexibility with remote or hybrid work arrangements, particularly in response to candidate needs and project requirements.
Johns Manville Software Engineer candidate reports ↗What topics does Johns Manville test in interviews?
Johns Manville interviews most often cover Communication Skills, Problem Solving, Phone Screening, Behavioral Interviewing, and Stakeholder Management. The exact emphasis depends on the specific role you apply for.
Johns Manville Software Engineer candidate reports ↗Sources & methodology 3 sources ↗
No official company page is cited. Rounds and questions come from candidate reports and PracHub editorial material; each source shows the date it was read.
- 01Johns Manville Software Engineer candidate reports ↗
Company-reported rounds, questions and FAQ.
Candidate reports · Accessed 2026-09-22 - 02PracHub Software Engineer practice ↗
PracHub practice material, not company-reported.
PracHub page · Accessed 2026-09-22 - 03PracHub preparation framework ↗
PracHub preparation guidance.
PracHub page · Accessed 2026-09-22
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